GHSA-4642-5mcj-2rqw: Forge: ASN.1 OID first arc truncation in asn1.oidToDer

  • Severity: LOW
  • CVE: CVE-2026-118775
  • Ecosystems: npm
  • Packages: node-forge

### 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 related encoding bug made valid OIDs with a first subidentifier above 127 (`2.48` and higher, e.g. `2.999`) encode and decode incorrectly, because the first subidentifier was always written and read as a single byte.

The fix rejects out-of-range first arcs and encodes and decodes the first subidentifier in base 128 like the others (the latter from public PR #1148).

### Patches
Fixed in node-forge 1.4.1. `asn1.oidToDer()` throws for OIDs with out-of-range first arcs, and the first subidentifier…

Source: GitHub Security Advisories · 2026-10-30