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Forge has signature forgery in RSA-PKCS due to ASN.1 extra field

Type: advisorySource: OSV1 source record

## Summary RSASSA PKCS#1 v1.5 signature verification accepts forged signatures for low public exponent keys (e=3). Attackers can forge signatures by stuffing “garbage” bytes within the ASN structure in order to construct a signature that passes verification, enabling [Bleichenbacher style forgery](https://mailarchive.ietf.org/arch/msg/openpgp/5rnE9ZRN1AokBVj3VqblGlP63QE/). This issue is similar to [CVE-2022-24771](https://github.com/digitalbazaar/forge/security/advisories/GHSA-cfm4-qjh2-4765), but adds bytes in an addition field within the ASN structure, rather than outside of it. Additionally, forge does not validate that signatures include a minimum of 8 bytes of padding as [defined by the specification](https://datatracker.ietf.org/doc/html/rfc2313#section-8), providing attackers additional space to construct Bleichenbacher forgeries. ## Impacted Deployments **Tested commit:** `8e1d527fe8ec2670499068db783172d4fb9012e5` **Affected versions:** tested on v1.3.3 (latest release) and recent prior versions. **Configuration assumptions:** - Invoke key.verify with defaults (default `scheme` uses RSASSA-PKCS1-v1_5). - `_parseAllDigestBytes: true` (default setting). ## Root Cause In `lib/rsa.js`, `key.verify(...)`, forge decrypts the signature block, decodes PKCS#1 v1.5 padding (`_decodePkcs1_v1_5`), parses ASN.1, and compares `capture.digest` to the provided digest. Two issues are present with this logic: 1. Strict DER byte-consumption (`_parseAllDigestBytes`) only guarantees all b

Announced Source revision 1
Original source ↗

GHSA-ppp5-5v6c-4jwp

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:GHSA-ppp5-5v6c-4jwp

node-forge

Source reference: /affected/0/package/name

Affected versions
Not stated in this record
Fixed versions
1.4.0

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "1.4.0"
          }
        ]
      }
    ],
    "package": {
      "name": "node-forge",
      "purl": "pkg:npm/node-forge",
      "ecosystem": "npm"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-ppp5-5v6c-4jwp/GHSA-ppp5-5v6c-4jwp.json"
    }
  }
]
Related CVEs
CVE-2026-33894

Source reference: /aliases

CVE-2026-85393

Source reference: /aliases

Publisher severity

high

Source reference: /database_specific/severity

Linked CVE context

These ratings describe the referenced vulnerabilities and products. They are not a severity rating for every application using this dependency.

CVE-2026-33894 · High

node-forge

CVE-2026-85393 · High

node-forge

Event
#63997 · Revision 1
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Publisher date
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