{"id":"CVE-2026-34876","aliases":["DEBIAN-CVE-2026-34876","EUVD-2026-18356","GHSA-jw9g-6hxw-4whq","UBUNTU-CVE-2026-34876","openSUSE-SU-2026:10498-1"],"status":"published","title":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in...","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"adp","from":"cve"},"epss":{"day":"2026-11-09","score":0.00406,"percentile":0.3511,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-125"],"published":"2026-04-02T00:00:00Z","modified":"2026-10-28T02:30:40Z","fixes":[{"ecosystem":"Debian:13","package":"mbedtls","fixed_in":["3.6.6-0.1~deb13u1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"mbedtls","fixed_in":["3.6.6-0.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.28.3-1","2.28.4-1","2.28.5-1","2.28.6-1","2.28.7-1","2.28.7-1.1","2.28.7-1.1~exp1","2.28.8-1","3.6.0-1","3.6.0-2","3.6.0-3","3.6.2-1","3.6.2-2","3.6.2-3","3.6.3-1","3.6.4-1","3.6.4-2","3.6.5-0.1","3.6.5-0.1~deb13u1","3.6.6-0.1","3.6.6-0.1~deb13u1","3.6.7-2","3.6.7-3"]},{"source":"osv","ecosystem":"Debian:13","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-0.1~deb13u1"}]}],"versions":["3.6.4-2","3.6.5-0.1","3.6.5-0.1~deb13u1"]},{"source":"osv","ecosystem":"Debian:14","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-0.1"}]}],"versions":["3.6.4-2","3.6.5-0.1","3.6.5-0.1~deb13u1","3.6.6-0.1~deb13u1"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.2-1","2.2.0-1","2.2.1-1","2.2.1-2","2.2.1-2ubuntu0.1","2.2.1-2ubuntu0.2","2.2.1-2ubuntu0.3"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5.1-1ubuntu1","2.6.0-1","2.7.0-2","2.8.0-1","2.8.0-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.16.2-1","2.16.3-1","2.16.4-1ubuntu2","2.16.4-1ubuntu2+esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.16.9-0.1ubuntu1","2.16.11-0.1ubuntu1","2.16.11-0.3","2.28.0-1","2.28.0-1build1","2.28.0-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.28.3-1","2.28.6-1ubuntu1","2.28.7-1ubuntu1","2.28.7-1.1ubuntu1","2.28.8-1","2.28.8-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.6.2-3ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.6.5-0.1ubuntu2","3.6.6-0.1ubuntu1","3.6.7-3ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.6.2-3ubuntu1","3.6.5-0.1ubuntu1","3.6.5-0.1ubuntu2"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-1.1"}]}],"bundled":10}],"products":[{"vendor":"trustedfirmware","product":"mbed_tls"}],"references":[{"url":"https://mbed-tls.readthedocs.io/en/latest/tech-updates/security-advisories/","tags":["Vendor Advisory","advisory"]},{"url":"https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-ccm-finish-boundary-check/","tags":["Vendor Advisory","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34876","tags":["advisory"]},{"url":"https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-ccm-finish-boundary-check"},{"url":"https://mbed-tls.readthedocs.io/en/latest/tech-updates/security-advisories"},{"url":"https://github.com/advisories/GHSA-jw9g-6hxw-4whq"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34876.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-34876","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-34876","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-34876","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2026-25833","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-25834","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-25835","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34871","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34872","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34873","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34874","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34875","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34876","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34877","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-34876","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","status":"published","published":"2026-04-02T00:00:00Z","modified":"2026-04-02T15:54:45.23Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"adp"}],"cwes":["CWE-125"],"updated_at":"2026-11-02T14:20:13.962274Z"}],"euvd":[{"id":"EUVD-2026-18356","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","status":"published","published":"2026-04-02T00:00:00Z","modified":"2026-04-02T15:54:45Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-02T19:25:22.606516Z"}],"ghsa":[{"id":"GHSA-jw9g-6hxw-4whq","title":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in...","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","status":"published","published":"2026-04-02T18:31:37Z","modified":"2026-04-02T18:31:45Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"cwes":["CWE-125"],"updated_at":"2026-11-02T15:07:05.449461Z"}],"nvd":[{"id":"CVE-2026-34876","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","status":"published","published":"2026-04-02T16:16:26.18Z","modified":"2026-07-24T21:10:00.143Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-125"],"updated_at":"2026-11-02T14:12:12.73929Z"}],"osv":[{"id":"CVE-2026-34876","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","status":"published","published":"2026-04-02T00:00:00Z","modified":"2026-10-28T02:30:40.41655034Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-02T15:45:02.673625Z"},{"id":"DEBIAN-CVE-2026-34876","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","status":"published","published":"2026-04-02T16:16:26.18Z","modified":"2026-10-01T03:03:03.986068991Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-02T15:45:54.587575Z"},{"id":"UBUNTU-CVE-2026-34876","description":"An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.","status":"published","published":"2026-04-02T16:16:00Z","modified":"2026-10-17T13:00:02.294038682Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-02T16:56:16.036833Z"},{"id":"openSUSE-SU-2026:10498-1","title":"libeverest-3.6.6-1.1 on GA media","description":"These are all security issues fixed in the libeverest-3.6.6-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-04-07T00:00:00Z","modified":"2026-04-08T07:50:16.855666Z","updated_at":"2026-11-02T16:58:38.415593Z"}]}}