GHSA-ppp5-5v6c-4jwp — Forge has signature forgery in RSA-PKCS due to ASN.1 extra field

Affected: npm: node-forge

## 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 guaran…

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GHSA-ppp5-5v6c-4jwp — Forge has signature forgery in RSA-PKCS due to ASN.1 extra field