{"id":"CVE-2026-6331","aliases":["ALPINE-CVE-2026-6331","DEBIAN-CVE-2026-6331","EUVD-2026-39565","GHSA-5hpf-pc4x-3jcf","JLSEC-2026-749","UBUNTU-CVE-2026-6331"],"status":"published","title":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","severity":{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.0019,"percentile":0.0871,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-347"],"published":"2026-06-25T20:56:25Z","modified":"2026-11-03T06:33:05Z","fixes":[{"ecosystem":"Alpine:v3.24","package":"wolfssl","fixed_in":["5.9.2-r0"],"sources":["osv"]},{"ecosystem":"Debian:12","package":"wolfssl","fixed_in":["5.5.4-2+deb12u3"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"wolfssl","fixed_in":["5.7.2-0.1+deb13u2"],"sources":["osv"]},{"ecosystem":"Julia","package":"wolfSSL_jll","fixed_in":["5.9.2+0"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Alpine:v3.24","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.15.5"},{"fixed":"5.9.2-r0"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.5.4-2+deb12u3"}]}],"versions":["5.5.4-2","5.5.4-2+deb12u1","5.5.4-2+deb12u2"]},{"source":"osv","ecosystem":"Debian:13","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.7.2-0.1+deb13u2"}]}],"versions":["5.7.2-0.1","5.7.2-0.1+deb13u1"]},{"source":"osv","ecosystem":"Julia","package":"wolfSSL_jll","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.9.2+0"}]}]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.8+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.10.2+dfsg-2","3.12.0+dfsg-1","3.12.2+dfsg-1","3.13.0+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.0+dfsg-2","4.2.0+dfsg-1","4.2.0+dfsg-2","4.2.0+dfsg-3","4.3.0+dfsg-2"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.6.0-3","5.0.0-1","5.1.1-1","5.2.0-1","5.2.0-2"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.5.4-2","5.5.4-2.1","5.6.4-2","5.6.6-1.2","5.6.6-1.3","5.6.6-1.3build1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.7.2-0.1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.9.1-0.1","5.9.2-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.7.2-0.1","5.8.2-1.2","5.8.4-1","5.9.1-0.1"]}],"products":[{"vendor":"wolfssl","product":"wolfssl"}],"references":[{"url":"https://github.com/wolfSSL/wolfssl/pull/10192","tags":["patch","Issue Tracking","Patch","fix","web","report"]},{"url":"https://www.wolfssl.com/docs/security-vulnerabilities/","tags":["Vendor Advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6331","tags":["advisory","web"]},{"url":"https://www.wolfssl.com/docs/security-vulnerabilities","tags":["web"]},{"url":"https://github.com/advisories/GHSA-5hpf-pc4x-3jcf","tags":["web"]},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-6331","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6331.json","tags":["advisory"]},{"url":"https://github.com/wolfSSL/wolfssl","tags":["package"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-6331","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-6331","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-6331","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-6331","title":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-25T20:56:25.876Z","modified":"2026-06-26T13:53:06.73Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low","assessor":"cna"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T13:50:04.986624Z"}],"euvd":[{"id":"EUVD-2026-39565","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-25T20:56:25Z","modified":"2026-06-26T13:53:06Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low"}],"updated_at":"2026-11-02T18:20:24.495602Z"}],"ghsa":[{"id":"GHSA-5hpf-pc4x-3jcf","title":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted...","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-26T00:32:06Z","modified":"2026-06-27T21:30:29Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"low"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T15:09:01.878033Z"}],"nvd":[{"id":"CVE-2026-6331","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-25T22:17:03.01Z","modified":"2026-06-27T19:48:56.343Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"low","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"primary"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T14:12:26.045561Z"}],"osv":[{"id":"ALPINE-CVE-2026-6331","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-25T22:17:03.01Z","modified":"2026-11-03T06:33:05.796257408Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-03T07:15:37.282377Z"},{"id":"CVE-2026-6331","title":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-25T20:56:25.876Z","modified":"2026-10-28T02:31:02.973555427Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T15:45:13.306117Z"},{"id":"DEBIAN-CVE-2026-6331","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-25T22:17:03.01Z","modified":"2026-10-01T03:03:29.249612948Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:45:57.932517Z"},{"id":"JLSEC-2026-749","title":"HMAC zero-length tag forgery in `EVP_DigestVerifyFinal`, where a zero-length tag could be accepted...","description":"HMAC zero-length tag forgery in `EVP_DigestVerifyFinal`, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-07-14T21:41:35.775Z","modified":"2026-07-25T18:24:51.878803015Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"},{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"low"}],"updated_at":"2026-11-02T15:47:19.003546Z"},{"id":"UBUNTU-CVE-2026-6331","description":"HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.","status":"published","published":"2026-06-25T22:17:00Z","modified":"2026-10-17T13:00:32.41728217Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"low"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T16:56:43.630667Z"}]}}