chore(deps): update vulnerable [security]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
form-data	4.0.5 → 4.0.6
js-yaml	4.1.1 → 4.2.0

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form-data: CRLF injection in form-data via unescaped multipart field names and filenames

CVE-2026-12143 / GHSA-hmw2-7cc7-3qxx

More information

Details

Summary

form-data builds multipart/form-data request bodies. Through v4.0.5, the field name passed to FormData#append and the filename option are concatenated directly into the Content-Disposition header with no escaping of CR (\r), LF (\n), or ". An application that uses untrusted input as a field name or filename therefore lets an attacker terminate the header line and either inject additional headers or smuggle whole additional multipart parts into the request the application forwards to a backend.

This is CWE-93 (CRLF injection). It is a divergence from how browsers and the WHATWG HTML spec serialize form-data (they escape these characters), so the fix is to match that behavior. Severity is conditional: it depends on the consuming application passing attacker-controlled data as a field name or filename. Applications that only use fixed/trusted field names are not affected.

Details

In lib/form_data.js, _multiPartHeader builds the part header as:

'Content-Disposition': ['form-data', 'name="' + field + '"'].concat(contentDisposition || [])

and _getContentDisposition builds filename="' + filename + '"'. Neither escapes control characters, so a \r\n in field/filename ends the header line. The same applies to ", which can break out of the quoted parameter.

Proof of concept

const FormData = require('form-data');
const form = new FormData();
form.append('email"\r\nX-Injected: true\r\nfake="', 'user@example.com');
console.log(form.getBuffer().toString());

Before the fix this emits an injected X-Injected: true header line. A field name that also includes --<boundary> sequences can introduce additional parts (e.g. an extra name="is_admin" field), which a downstream parser accepts as legitimate.

Impact

For an application that uses untrusted field names/filenames:

• Field injection / override (integrity). Inject or override fields the backend trusts (e.g. is_admin, role) — the primary demonstrated impact.
• Header injection into the generated multipart part.

Claims of guaranteed privilege escalation, authentication bypass, high confidentiality impact, and availability impact are application-dependent downstream consequences, not properties of form-data itself, and are not demonstrated by the PoC.

Severity

The demonstrated, library-attributable impact is integrity (field/header injection); there is no demonstrated confidentiality disclosure or availability impact in form-data itself, and exploitation requires the consuming app to feed untrusted data into field names/filenames. A Moderate (≈5.3, I:L) rating is also defensible given that precondition.

Patch

Fixed in 4.0.6, 3.0.5, and 2.5.6. Users on older 0.x/1.x/2.x releases should upgrade to 2.5.6 or later.

The fix escapes \r, \n, and " as %0D, %0A, and %22 in field names and filenames, matching the WHATWG HTML multipart/form-data encoding algorithm that browsers implement. This neutralizes the injection while leaving ordinary field names (including name[0], dotted, and unicode names) unchanged.

Workaround

Until upgrading, validate or reject field names/filenames that contain control characters before calling append:

if (/[\r\n]/.test(field)) { throw new Error('invalid field name'); }

Credit

Reported by yueyueL.

Severity

• CVSS Score: 8.7 / 10 (High)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

References

• https://github.com/form-data/form-data/security/advisories/GHSA-hmw2-7cc7-3qxx
• https://nvd.nist.gov/vuln/detail/CVE-2026-12143
• https://github.com/form-data/form-data/commit/64190db548c0179e37206858e39f27cf513e9435
• https://github.com/form-data/form-data/commit/be3f3cf553978bac15a5182f1f3c3d2d38ccf229
• https://github.com/form-data/form-data/commit/c7133499c2ee1b80c678e411244f4442bf902045
• https://github.com/form-data/form-data
• https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#multipart-form-data
• https://www.npmjs.com/package/form-data

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

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JS-YAML: Quadratic-complexity DoS in merge key handling via repeated aliases

CVE-2026-53550 / GHSA-h67p-54hq-rp68

More information

Details

Summary

A crafted YAML document can trigger algorithmic CPU exhaustion in js-yaml merge-key processing (<<) by repeating the same alias many times in a merge sequence.
This causes quadratic parse-time behavior relative to input size and can block a Node.js worker/event loop for seconds with a relatively small payload (tens of KB), resulting in denial of service.

Details

The issue is in merge handling inside lib/loader.js:

• storeMappingPair(...) iterates every element of a merge sequence when key tag is tag:yaml.org,2002:merge.
• For each element, it calls mergeMappings(...).
• mergeMappings(...) computes Object.keys(source) and performs _hasOwnProperty.call(destination, key) checks for each key.

When input is of the form:

a: &a {k0:0, k1:0, ..., kK:0}
b: {<<: [*a, *a, *a, ... repeated M times ...]}
all *a entries refer to the same anchored object. After the first merge, subsequent merges are semantically no-ops, but the parser still reprocesses all keys each time.
Resulting work is O(K * M), while input size is O(K + M), giving quadratic scaling as payload grows.
Relevant code path:
lib/loader.js in storeMappingPair(...) merge branch (keyTag === 'tag:yaml.org,2002:merge')
lib/loader.js mergeMappings(...)

Root cause

File: lib/loader.js
Function: storeMappingPair(state, _result, overridableKeys, keyTag, keyNode,
valueNode, startLine, startLineStart, startPos)
Lines: ~359-366

if (keyTag === 'tag:yaml.org,2002:merge') {
  if (Array.isArray(valueNode)) {
    for (index = 0, quantity = valueNode.length; index < quantity; index += 1) {
      mergeMappings(state, _result, valueNode[index], overridableKeys);
    }
  } else {
    mergeMappings(state, _result, valueNode, overridableKeys);
  }
}

When the merge value is a sequence (YAML 1.1 <<: [ *a, *a, ... ]), each element
is handed to mergeMappings() without deduplication. mergeMappings() then does

sourceKeys = Object.keys(source);
for (index = 0; index < sourceKeys.length; index += 1) {
  key = sourceKeys[index];
  if (!_hasOwnProperty.call(destination, key)) {
    setProperty(destination, key, source[key]);
    overridableKeys[key] = true;
  }
}

Every alias reference in the sequence resolves (by design) to the SAME object
via state.anchorMap. After the first merge, every subsequent merge of that same
reference is a pure no-op semantically, but still performs:

• one Object.keys(source) call (O(K))
• K _hasOwnProperty.call checks on the destination

Total: M * K hasOwnProperty checks + M Object.keys allocations, while the final
object and all observable side effects are identical to a single merge.

YAML semantics for <<: are idempotent and commutative over duplicate sources,
so collapsing duplicates preserves behavior exactly; this isn't a spec trade-off.

PoC

Environment:
js-yaml version: 4.1.1
Node.js: v24.5.0
Platform: arm64 macOS (reproduced consistently)
Reproduction script:
Create many keys in one anchored map (&a).
Merge that same alias repeatedly via <<: [*a, *a, ...].
Measure parse time and compare with control payload using single merge (<<: *a).
Observed repeated runs (same machine):
K=M=1000, input 9,909 bytes: ~33–36 ms
K=M=2000, input 20,909 bytes: ~121–123 ms
K=M=4000, input 42,909 bytes: ~524–537 ms
K=M=6000, input 64,909 bytes: ~1,608–1,829 ms
K=M=8000, input 86,909 bytes: ~3,395–3,565 ms
Control (single merge, similar key counts):
K=2000: ~1–2 ms
K=4000: ~3 ms
K=8000: ~5 ms
Also verified: repeated-merge output equals single-merge output (same key count and same JSON), confirming excess time is redundant computation.

Impact

This is a denial-of-service vulnerability (CPU exhaustion / algorithmic complexity).
Any service parsing untrusted YAML with js-yaml can be impacted, including API backends, CI tools, config processors, and automation services. An attacker can submit crafted YAML to significantly increase CPU time and reduce availability.

Suggested fix:

Dedupe the merge source list by reference before invoking mergeMappings. Any of
the following are minimal and preserve YAML 1.1 merge semantics:

dedupe in storeMappingPair:

if (keyTag === 'tag:yaml.org,2002:merge') {
  if (Array.isArray(valueNode)) {
    var seen = new Set();
    for (index = 0, quantity = valueNode.length; index < quantity; index += 1) {
      var src = valueNode[index];
      if (seen.has(src)) continue;   // idempotent; skip redundant alias
      seen.add(src);
      mergeMappings(state, _result, src, overridableKeys);
    }
  } else {
    mergeMappings(state, _result, valueNode, overridableKeys);
  }
}

Severity

• CVSS Score: 5.3 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

• https://github.com/nodeca/js-yaml/security/advisories/GHSA-h67p-54hq-rp68
• https://github.com/nodeca/js-yaml

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

---

Release Notes

form-data/form-data (form-data)

v4.0.6

Compare Source

nodeca/js-yaml (js-yaml)

v4.2.0

Compare Source

Added

• Added docs/safety.md with notes about processing untrusted YAML.
• Added maxDepth (100) loader option. Not a problem, but gives a better
  exception instead of RangeError on stack overflow.
• Added maxMergeSeqLength (20) loader option. Not a problem after merge fix,
  but an additional restriction for safety.
• Added sourcemaps to dist/ builds.

Changed

• Stop resolving numbers with underscores as numeric scalars, #​627.
• Switched dev toolchains to Vite / neostandard.
• Updated demo.
• Reorganized tests.
• dist/ files are no longer kept in the repository.

Fixed

• Fix parsing of properties on the first implicit block mapping key, #​62.
• Fix trailing whitespace handling when folding flow scalar lines, #​307.
• Reject top-level block scalars without content indentation, #​280.
• Ensure numbers survive round-trip, #​737.
• Fix test coverage for issue #​221.
• Fix flow scalar trailing whitespace folding, #​307.
• Fix digits in YAML named tag handles.

Security

• Fix potential DoS via quadratic complexity in merge - deduplicate repeated
  elements (makes sense for malformed files > 10K).

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