{"id":"GHSA-9wg5-mj3p-v49q","summary":"Forge: Certificate signature verified with the issuer's RSA signature scheme","details":"### Summary\n\nWhen verifying a certificate, node-forge chose the RSA padding scheme (PKCS#1 v1.5 or RSASSA-PSS) and PSS parameters from the issuer certificate's own signature algorithm instead of the certificate being verified. A certificate labeled as signed with RSASSA-PSS could pass `verifyCertificateChain()` with a PKCS#1 v1.5 signature. Fixed in node-forge 1.4.1.\n\n### Details\n\n`certificate.verify(child)` in `lib/x509.js` hashes the child's TBSCertificate with the digest of the child's signature algorithm, then calls `_verifySignature()` with the issuer certificate. `_verifySignature()` selected the padding scheme from that certificate's `signatureOid` and `signatureParameters`, so the child was verified with the issuer's own scheme rather than the one the child declares.\n\nAs a result, a child certificate whose signature algorithm says RSASSA-PSS was accepted with a PKCS#1 v1.5 signature when the issuer itself was signed with PKCS#1 v1.5. The outer `signatureAlgorithm` field of a certificate is not covered by the signature, so an existing PKCS#1 v1.5 (SHA-256) certificate can be relabeled as RSASSA-PSS and still pass verification. The signature itself must still be made with the issuer's private key over the certificate's contents; no certificate can be forged.\n\nThe same cause made correctly signed chains fail: a PKCS#1 v1.5 certificate issued by an RSASSA-PSS-signed certificate, or the reverse, was rejected.\n\nThe fix verifies with the child certificate's signature scheme and parameters and the issuer's public key.\n\n### Patches\nFixed in node-forge 1.4.1. Certificate signatures are verified with the scheme of the certificate's own signature algorithm.\n\n### Workarounds\nApplications that make decisions based on a certificate's signature algorithm can verify the signature themselves with that algorithm's scheme and the issuer's public key.\n\n### References\n- https://www.rfc-editor.org/rfc/rfc4055#section-3 (RSASSA-PSS signature algorithm in certificates)\n- https://www.rfc-editor.org/rfc/rfc5280#section-4.1.1.2 (Certificate signatureAlgorithm)\n- https://cwe.mitre.org/data/definitions/347.html (CWE-347: Improper Verification of Cryptographic Signature)\n\n### Severity\nCVSS 3.1: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N (3.7, Low)\nCVSS 4.0 (informational): CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N (6.3)\nCVSS 4.0 rates this Moderate because its integrity weighting is higher; the severity rating follows CVSS 3.1.\n\n### Credits\nReported by Brian Lee (@hibrian827, Georgia Tech SSLab, Team Atlanta), who also suggested the fix.\n\n### Proof of concept\n\nCreate a CA certificate signed with sha256WithRSAEncryption, and a leaf certificate whose signature algorithm fields (outer and in the TBSCertificate) are RSASSA-PSS with SHA-256/MGF1-SHA-256/salt 32, but sign the leaf's TBSCertificate with the CA key using PKCS#1 v1.5 (`caKey.sign(sha256)`).\n\nOn 1.4.0, `forge.pki.verifyCertificateChain(forge.pki.createCaStore([ca]), [leaf])` returns `true`, although verifying the leaf's signature with RSASSA-PSS fails. On 1.4.1 it throws \"Certificate signature is invalid.\".\n\nNo private key is needed for the same result: take any certificate signed by the CA with sha256WithRSAEncryption and replace only its outer signatureAlgorithm (outside the signed TBSCertificate) with the RSASSA-PSS identifier above. On 1.4.0 it still verifies and reports `signatureOid` as RSASSA-PSS; on 1.4.1 it is rejected.\n\nRegression tests are in tests/unit/x509.js (\"signature scheme of the child certificate\").\n\n### Impact\n\nApplications that rely on a certificate's declared signature algorithm, for example a policy that only accepts RSASSA-PSS-signed certificates, can be given a certificate labeled RSASSA-PSS whose signature was verified as PKCS#1 v1.5. The certificate must still have been signed by the trusted issuer's key, so the identity it certifies cannot be forged. There is no confidentiality or availability impact.","aliases":["CVE-2026-118774"],"modified":"2026-11-10T16:15:04.153166136Z","published":"2026-11-10T15:57:48Z","database_specific":{"nvd_published_at":"2026-10-29T19:17:19Z","cwe_ids":["CWE-347"],"severity":"LOW","github_reviewed":true,"github_reviewed_at":"2026-11-10T15:57:48Z"},"references":[{"type":"WEB","url":"https://github.com/digitalbazaar/forge/security/advisories/GHSA-9wg5-mj3p-v49q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118774"},{"type":"WEB","url":"https://github.com/digitalbazaar/forge/commit/c7f42614d5166a77ddf11ce174b2601b14f6956b"},{"type":"PACKAGE","url":"https://github.com/digitalbazaar/forge"},{"type":"WEB","url":"https://github.com/digitalbazaar/forge/releases/tag/v1.4.1"}],"affected":[{"package":{"name":"node-forge","ecosystem":"npm","purl":"pkg:npm/node-forge"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.4.1"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 1.4.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/11/GHSA-9wg5-mj3p-v49q/GHSA-9wg5-mj3p-v49q.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}