CVE-2026-33894: Forge has signature forgery in RSA-PKCS due to ASN.1 extra field

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-27 · updated 2026-10-26
Weakness: CWE-20

Description

Forge (also called `node-forge`) is a native implementation of Transport Layer Security in JavaScript. Prior to version 1.4.0, 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. This issue is similar to CVE-2022-24771, 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, providing attackers additional space to construct Bleichenbacher forgeries. Version 1.4.0 patches the issue.

Affected products

digitalbazaar forge: before 1.4.0 — fixed in 1.4.0
Npm Node-Forge: before 1.4.0 — fixed in 1.4.0

How to fix

Upgrade to a fixed version: digitalbazaar forge 1.4.0; Npm Node-Forge 1.4.0. Check the vendor advisory for mitigations.

References

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