fix(deps): bump next to 15.5.28 (Next.js security update, Oct 14 2026)

[cosminraduUPTH]

Next.js security update (October 14, 2026)

This PR bumps next to 15.5.28 and regenerates the lockfile(s). It was opened by Claude Code as part of the Security team's Next.js remediation campaign and has not been validated by the repo owners yet.

Why

Vercel shipped an out-of-band security release on 2026-10-14 for three issues, all fixed in 16.4.1 (16.x line) and 15.5.28 (15.x line). Older majors have no fixed release.

• GHSA-673q-mjm6-r5xr (Critical). Unauthenticated remote code execution when a use cache function returns multiple typed arrays. Requires App Router with Cache Components. Vercel recommends upgrading even if you do not use this feature.
• CVE-2026-96889 / GHSA-2464-fhr4-w9xw (Critical). Unauthenticated remote code execution through the Image Optimization API with SVG input, caused by the upstream sharp library on glibc Linux. Fixed by sharp 0.35.5 or newer, which the patched Next.js releases pull in.
• GHSA-p3m5-59mp-jv5r (High). CPU-exhaustion denial of service against App Router apps that expose at least one Server Action.

Advisory: https://nextjs.org/blog/nextjs-security-update-october-14-2026

What changes

path	package	from	to
evalboard/package.json	next	^15.5.20	^15.5.28

What we need from you

1. Review the diff and let CI run.
2. Validate the app the way you normally would (build, smoke test the pages that use images or Server Actions).
3. Merge when you are satisfied, then make sure the change is deployed.

If this repository is no longer used, say so in the campaign Slack thread and we will archive it instead of patching.

Notes

• Dependabot PR(s) chore(deps): bump next from 15.5.22 to 15.5.24 in /evalboard #160, chore(deps): bump the npm-all group across 1 directory with 19 updates #210 target an older release and are superseded by this change.

• Lockfiles were regenerated with install scripts disabled.

• Campaign channel: #sec-campaign-nextjs-oct2026

🤖 Generated with Claude Code

[github-actions]

Claude finished @cosminraduUPTH's task in 1m 10s —— View job

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Security PR Review

Todo List:

• Read .github/code_review.md for review standards
• Read CLAUDE.md for project conventions
• Review git diff origin/main...HEAD
• Review full context of changed files
• Perform security-focused review
• Check dependency updates address stated CVEs
• Verify no missing updates or issues
• Submit comprehensive review

Working on review...

[uipreliga]

Review: coder_eval — pr:226 (2 files) axis:1,2,3,4,5,6,7,8

Scope: pr:226 (2 files) axis:1,2,3,4,5,6,7,8 · branch security/nextjs-cve-oct-2026 (pr-226) · 73690e4 · 2026-10-16T15:16Z · workflow variant

Change class: trivial — dependency/lockfile bump only (evalboard next ^15.5.20 → ^15.5.28); no source logic touched

The codebase is in good condition: seven of eight axes score 10/10, and no finding can change a task's score or final_status for identical agent output. The one real risk is in the evalboard (Security 8.9/10): this PR is a security update, but the lockfile still pins the vulnerable sharp 0.34.5 under next@15.5.28, and the live /_next/image path can send agent-written run artifacts to it. Fix the lockfile and the PR description before you merge.

Summary

Axis	Score	🔴	🟠	🟡	🔵	Top Issue
1. Code Quality & Style	10 / 10	0	0	0	0	—
2. Type Safety	10 / 10	0	0	0	0	—
3. Test Health	10 / 10	0	0	0	0	—
4. Security	8.9 / 10	0	1	0	1	Lockfile keeps vulnerable sharp 0.34.5 under next@15.5.28, although the PR body says it fixes CVE-2026-96889 / GHSA-2464-fhr4-w9xw (Image Optimization RCE). The /_next/image path is live and can fetch artifacts that agents write.
5. Architecture & Design	10 / 10	0	0	0	0	—
6. Error Handling & Resilience	10 / 10	0	0	0	0	—
7. API Surface & Maintainability	10 / 10	0	0	0	0	—
8. Evaluation Harness Quality	10 / 10	0	0	0	0	—

Overall Score: 9.9 / 10 · Weakest Axis: Security at 8.9 / 10
Totals: 🔴 0 · 🟠 1 · 🟡 0 · 🔵 1 across 8 axes.

Blockers

1. [Axis 4] Lockfile keeps vulnerable sharp 0.34.5 under next@15.5.28, although the PR body says it fixes CVE-2026-96889 / GHSA-2464-fhr4-w9xw (Image Optimization RCE). The /_next/image path is live and can fetch artifacts that agents write. (evalboard/pnpm-lock.yaml:4485) — The snapshot block next@15.5.28(@babel/core@7.29.7)(react-dom@19.2.8(react@19.2.8))(react@19.2.8): (line 4467) ends its optionalDependencies with sharp: 0.34.5 (line 4485), and the package entry is sharp@0.34.5: (line 2143). This is the same pin as main (origin/main lockfile line 4490), so the regeneration did not change it. next@15.5.28 declares "sharp": "^0.34.3 || ^0.35.5" (node_modules/next/package.json:114). 0.34.5 still satisfies that range, so pnpm kept the existing resolution. The cause is this range, not the disabled install scripts. On PR HEAD, pnpm audit --prod still reports 3 HIGH sharp advisories on the path .>next>sharp: GHSA-wq5f-xc86-pv6w (librsvg, CVE-2026-96889, fixed in >=0.35.5), GHSA-rgj7-g3m4-5g8c (libheif, fixed in >=0.35.4) and GHSA-f88m-g3jw-g9cj (libvips, fixed in >=0.35.0). The PR body says the patched Next.js releases pull in sharp 0.35.5 or newer. For this lockfile, that is false.

Reachability: the app uses next/image with the default loader (app/layout.tsx:2, app/_components/harness-badge.tsx:1), so the standalone server exposes /_next/image. next.config.mjs is { output: "standalone" }, which sets no images.localPatterns. hasLocalMatch returns true when localPatterns is undefined ("we allow all local images"), and the query string is kept. As a result, /_next/image?url=/api/file?run=..&path=.. sends the bytes of a run artifact to sharp. Agents under evaluation write those artifacts, and they are stored in blob containers (runs, runs-gha). PNG, JPEG, GIF, TIFF and WebP input reaches the vulnerable libvips loaders. next@15.5.28 keeps VipsForeignLoadSvg unblocked, and its SVG gate depends only on a magic-byte sniff plus dangerouslyAllowSVG (default false). The SVG-specific CVE is therefore not proven reachable in the default config. That is why AC is High, not Low.

Fix: in evalboard/package.json, add "sharp": "^0.35.5" to the existing pnpm.overrides block (package.json lines 43-47 already override postcss, fast-xml-builder, @babel/core and uuid; there is no override for sharp). Then regenerate pnpm-lock.yaml and confirm that pnpm ls next sharp shows sharp >=0.35.5 and that pnpm audit --prod has no sharp advisories. Correct the PR body claim. Defense in depth (outside this PR's files): set images.localPatterns to /harness/** and /uipath.png in next.config.mjs, so the optimizer cannot fetch /api/file. Add a pnpm audit --prod --audit-level high step to the evalboard CI job, which today runs only install, tsc, vitest and build, so a lockfile with this defect passes. CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Non-blocking, but please consider before merge

None.

Nits

1. [Axis 4] Lockfile still resolves nanoid 3.3.17 and source-map-js 1.2.1 under next>postcss (HIGH advisories). Both run at build time only and were already on main. (evalboard/pnpm-lock.yaml:4465) — The lockfile has nanoid@3.3.17: {} (line 4465; package entry line 1853) and source-map-js@1.2.1: {} (line 4832; package entry line 2162), both reached through postcss@8.5.23 (line 4586). pnpm audit --prod on PR HEAD flags GHSA-2v37-7h3g-55p8 (nanoid <3.3.18, infinite loop with size 0 in custom generators) and GHSA-68fv-2mgg-jv7q (source-map-js <1.2.2, event-loop DoS from indexed source-map section offsets). Both are on the paths .>next>postcss. postcss under next processes CSS during next build, and no request input reaches these packages at runtime, so the severity is Low. The PR did not add them. But this PR is the security remediation that regenerates this lockfile, and after it pnpm audit still exits 1 with 5 HIGH advisories. Fix: add "nanoid": "^3.3.18" and "source-map-js": "^1.2.2" to the existing pnpm.overrides in evalboard/package.json, next to "postcss": "^8.5.10". Then regenerate the lockfile so that pnpm audit --prod is clean. CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L

What's Missing

Parallel paths:

• 🟠 Parallel paths: the PR bumps next in evalboard/package.json, but the existing pnpm.overrides block (lines 43-47: postcss, fast-xml-builder, @babel/core, uuid) gets no matching sharp: ^0.35.5 entry. next@15.5.28's optional range ^0.34.3 || ^0.35.5 lets pnpm keep sharp 0.34.5, so the image-optimizer half of the advisory set stays unpatched. The fix needs both the next bump and the transitive sharp floor. (trigger: evalboard/package.json) (restates: Axis 4: Lockfile keeps vulnerable sharp 0.34.5 under next@15.5.28)
• 🟡 Parallel paths: the Python lockfile has two security gates in pr-checks.yml (pip-audit and osv-scanner). evalboard/pnpm-lock.yaml has neither. The osv-scanner step comment says the lockfile is 'intentionally out of scope ... widen scope in a follow-up once those packages have a maintainer-owned bump cadence'. Dependabot now provides that cadence (monthly npm-all group), and this PR is a security remediation of the same lockfile, but the PR does not widen osv-scanner or add pnpm audit --prod --audit-level high to the evalboard job. As a result, a lockfile that still resolves 5 HIGH advisories passes CI. (trigger: evalboard/pnpm-lock.yaml) (restates: Axis 4: Lockfile keeps vulnerable sharp 0.34.5 under next@15.5.28)
• 🔵 Parallel paths: the same regenerated lockfile still resolves nanoid 3.3.17 and source-map-js 1.2.1 under next>postcss (HIGH advisories, build-time only). The PR that regenerates the lockfile for security reasons does not add the nanoid ^3.3.18 / source-map-js ^1.2.2 overrides next to the existing postcss override. (trigger: evalboard/package.json) (restates: Axis 4: Lockfile still resolves nanoid 3.3.17 and source-map-js 1.2.1 under next>postcss)

Tests:

• 🟡 Tests: nothing checks that the resolved versions fix what the PR claims. The evalboard CI job (make evalboard-verify = frozen install + tsc + vitest + next build) only proves the app still builds. No step checks pnpm ls sharp >= 0.35.5 or that pnpm audit --prod is clean, so the false claim in the PR body ('patched Next.js releases pull in sharp 0.35.5 or newer') passed every gate. A regression gate must read the resolved dependency graph, so it has to run in CI and cannot be a static check on package.json alone. (trigger: evalboard/pnpm-lock.yaml) (restates: Axis 4: Lockfile keeps vulnerable sharp 0.34.5 under next@15.5.28)

Nightly pipeline:

• 🔵 Daily/nightly: the evalboard is not built or deployed from this repo (docker/Dockerfile and docker-publish.yml do not include it). The hosted board reads the runs / runs-gha blob containers that the nightly pipeline writes. The PR body does not say whether the hosted instance must be rebuilt and redeployed to receive the fix, or who owns that redeploy. Until the redeploy happens, the deployed /_next/image and Server Action endpoints keep the old next and sharp, whatever the lockfile on main says. (trigger: evalboard/package.json)

Harness & Lint Improvements

Static checks (lint / type):

• [ci-gate] Add a lockfile audit step to the evalboard job in .github/workflows/pr-checks.yml, after 'Install dependencies (lockfile-pinned)': pnpm audit --prod --audit-level high (working-directory: evalboard). Mirror it in the Makefile evalboard-verify target (cd evalboard && pnpm install --frozen-lockfile && pnpm audit --prod --audit-level high && pnpm verify) so the local check matches CI. Accepted build-time-only advisories go in pnpm.auditConfig.ignoreGhsas in evalboard/package.json, each with a reason and a revisit date. This follows the existing pip-audit --ignore-vuln / osv-scanner.toml pattern. Audit reads only the lockfile and the advisory DB, and needs no app runtime, so it fits as a CI gate. Prevents: Finding 1 (HIGH): sharp 0.34.5 under next@15.5.28 in evalboard/pnpm-lock.yaml:4485/2143. On PR HEAD, pnpm audit --prod already reports GHSA-wq5f-xc86-pv6w, GHSA-rgj7-g3m4-5g8c and GHSA-f88m-g3jw-g9cj on .>next>sharp, so this gate would have failed the PR and disproved the PR-body claim that sharp >=0.35.5 is pulled in. Finding 2 (LOW): nanoid 3.3.17 / source-map-js 1.2.1 under next>postcss (GHSA-2v37-7h3g-55p8, GHSA-68fv-2mgg-jv7q). The gate fails until they are overridden or allowlisted with a reason. Today the evalboard job runs only install, tsc, vitest and build, so a security-remediation PR with this defect passes.
• [ci-gate] Widen the existing 'Security - OSV vulnerability scan (osv-scanner)' step in pr-checks.yml from --lockfile=uv.lock to also scan --lockfile=evalboard/pnpm-lock.yaml, and add any npm suppressions to osv-scanner.toml with a reason. The step comment already names evalboard/pnpm-lock.yaml as 'intentionally out of scope ... widen scope in a follow-up'. This PR is that follow-up. The binary is pinned by sha256, so this is a second, independent advisory source for the same lockfile (OSV.dev, next to the npm registry advisories that pnpm audit uses). Prevents: Findings 1 and 2. All five HIGH advisories (three sharp, nanoid, source-map-js) are GHSA entries that OSV.dev aggregates, so the quality-gate job would also have failed the lockfile, even if the pnpm-audit step were skipped or allowlisted too broadly.
• [ce-lint] CE069 (next free id per tests/lint/runner.py: 'Claim 069 next'), a doc-surface/whole-tree rule as a @pytest.mark.lint class TestCE069EvalboardImageOptimizerScoped in tests/test_custom_lint.py. It is not an AST rule in tests/lint/rules/, because it reasons over JS/TS text, like CE065. Invariant: if any file under evalboard/app/** imports next/image, then evalboard/next.config.mjs must declare images.localPatterns (an explicit allowlist, today /harness/** and /uipath.png) or images.unoptimized: true. It must also not declare images.remotePatterns/domains with a wildcard host. Forbidden pattern: Next's default 'allow all local images' optimizer, which lets /_next/image?url=/api/file?... send agent-written run artifacts to sharp. Known blind spot: a regex parse of next.config.mjs cannot see a config that is built dynamically. The rule should fail closed if it cannot find the images key. Prevents: The reachability half of Finding 1. next.config.mjs is only { output: "standalone" }, and app/layout.tsx:2 and app/_components/harness-badge.tsx:1 import next/image, so hasLocalMatch allows /api/file. With CE069, the optimizer cannot fetch untrusted artifacts, even when a future sharp/libvips advisory lands before the lockfile is bumped.

Harness improvements (not statically reachable):

• Security-remediation PR evidence rule: when a PR title or commit is security: and touches evalboard/pnpm-lock.yaml (or uv.lock), the PR body must include before and after output of pnpm why <pkg> / pnpm ls next sharp and pnpm audit --prod. Do not paraphrase the upstream changelog. Add this to the PR template and to the coder-eval-code-review security axis checklist ('verify every claimed transitive version against the lockfile'). Why not static: To check that prose in a PR body matches the resolved lockfile, a tool must understand the natural-language claim ('pulls in sharp 0.35.5 or newer') and the reason for it. The audit gate catches the vulnerable pin, but it cannot catch a false claim about a package that has no current advisory. Prevents: Finding 1: the PR body claimed that the Next.js bump fixed CVE-2026-96889 through sharp >=0.35.5. The ^0.34.3 || ^0.35.5 range in next/package.json:114 let pnpm keep 0.34.5, and nobody ran pnpm ls sharp to confirm the claim.
• Add an evalboard integration test (vitest + the built standalone server, or a Playwright smoke test in the evalboard CI job). It requests /_next/image?url=%2Fapi%2Ffile%3Frun%3Dx%26path%3Dy&w=64&q=75 and asserts a 400 response ('url parameter is not allowed'). A second request to /_next/image?url=%2Fuipath.png... must still return 200. Why not static: Next.js resolves the effective optimizer policy at runtime: localPatterns defaulting, query-string handling and the matcher in match-local-pattern.js. Only a running server proves that /api/file is unreachable through the optimizer, and the result can change across Next versions even when next.config.mjs does not change. Prevents: The exposure path in Finding 1 (/_next/image -> /api/file -> agent-written artifact -> vulnerable libvips/libheif loaders in sharp). It also catches a Next upgrade that changes localPatterns semantics after CE069's static check passes.
• Change the evalboard npm block in .github/dependabot.yml so that security updates are not held to the monthly grouped schedule. Enable Dependabot security updates for /evalboard, and add an npm-security group with applies-to: security-updates. Then a sharp/nanoid/source-map-js advisory opens a PR at once, and it covers transitive dependencies through overrides. Why not static: An advisory is published after merge, so its timing depends on an external feed. A gate that runs at PR time cannot see an advisory published later against an unchanged lockfile. Prevents: Findings 1 and 2 both describe advisories that were already on main (origin/main lockfile line 4490 has the same sharp pin, and nanoid/source-map-js were present before this PR). They were found only by a manual review of a security PR, not by an automated alert-to-PR loop.

Top 5 Priority Actions

1. No finding changes a task's score or final_status, so the most urgent fix is the HIGH one: add "sharp": "^0.35.5" to pnpm.overrides in evalboard/package.json (lines 43-47), regenerate evalboard/pnpm-lock.yaml (sharp pin at line 4485, package entry at line 2143), confirm with pnpm ls next sharp and pnpm audit --prod that there are no sharp advisories, and correct the PR body's false claim that the patched Next.js release pulls in sharp 0.35.5 or newer.
2. Close the path from the optimizer to agent artifacts: next.config.mjs is only { output: "standalone" }, so /_next/image?url=/api/file?... sends run artifacts to libvips. Set images.localPatterns to allow only /harness/** and /uipath.png.
3. Add a pnpm audit --prod --audit-level high step to the evalboard CI path (Makefile:86, which today runs only pnpm install --frozen-lockfile && pnpm verify), so a lockfile with a known HIGH advisory fails the build.
4. Add "nanoid": "^3.3.18" and "source-map-js": "^1.2.2" to pnpm.overrides next to postcss, then regenerate evalboard/pnpm-lock.yaml (nanoid at line 4465, source-map-js at line 4832). This makes pnpm audit --prod exit 0. Both packages run only at build time, so the risk is Low.
5. After you regenerate the lockfile, run make evalboard-verify (tsc, vitest, next build). Then do a short smoke test of next/image rendering (app/layout.tsx:2, app/_components/harness-badge.tsx:1) to confirm that the move from sharp 0.34 to 0.35 does not break image optimization in the standalone build.

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Stats: 0 🔴 · 1 🟠 · 0 🟡 · 1 🔵 across 8 axes reviewed.