Forge: ASN.1 OID first arc truncation in asn1.oidToDer

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

• CVE-2026-118775: 0.31% estimated exploitation activity in the next 30 days; percentile 24.31 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary `asn1.oidToDer()` did not range-check the first two arcs of an OID string, so an OID such as `0.42.840.113549.1.1.1` or `4294977127.18.840.113549.1.1.1` was encoded as the DER of a different OID (here rsaEncryption, `1.2.840.113549.1.1.1`). This is an incomplete fix of CVE-2025-66030. Fixed in node-forge 1.4.1.

Details X.690 section 8.19 encodes the first two arcs of an OID as one subidentifier, `40 * arc1 + arc2`, where the first arc is 0, 1 or 2 and the second arc is at most 39 when the first is 0 or 1. `asn1.oidToDer()` in `lib/asn1.js` computed that value with no range check and wrote it with `putByte()`, which keeps only the low 16 bits. Out-of-range first arcs therefore produced the encoding of a different OID: `0.42.840.113549.1.1.1` gives `40 * 0 + 42 = 42` and `4294977127.18.840.113549.1.1.1` wraps to 42, both the first byte of rsaEncryption. The fix for CVE-2025-66030 (GHSA-65ch-62r8-g69g, node-forge 1.3.2) added a 32-bit check for the later arcs only. A…

Published by the source

30 Oct 2026, 23:02 UTC

Last modified by the source

30 Oct 2026, 23:15 UTC

Source last checked

31 Oct 2026, 06:00 UTC

1. Revision 2 · amended · 31 Oct 2026

   Amended from osv record GHSA-4642-5mcj-2rqw

2. Revision 1 · created · 30 Oct 2026

   Published from ghsa record GHSA-4642-5mcj-2rqw

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# Patch Next advisory brief: CVE-2026-118775

Advisory: Forge: ASN.1 OID first arc truncation in asn1.oidToDer
IDs: CVE-2026-118775, GHSA-4642-5mcj-2rqw
Record: https://patchnext.com/advisories/cve-2026-118775 (revision 2, source checked 31 Oct 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: node-forge 1.4.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm node-forge: affected < 1.4.1; fixed in 1.4.1

## Suggested inspection (read-only)
- `npm ls node-forge --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on node-forge.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4642-5mcj-2rqw (GitHub-reviewed advisory GHSA-4642-5mcj-2rqw lists affected ranges: npm node-forge >=0 <=1.4.0)
- Verified: https://osv.dev/vulnerability/GHSA-4642-5mcj-2rqw (OSV record GHSA-4642-5mcj-2rqw lists affected ranges: npm node-forge >=0 <1.4.1 (fixed))

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