{"id":"CVE-2026-6691","aliases":["DEBIAN-CVE-2026-6691","EUVD-2026-27838","GHSA-587q-94wg-2pfp","OESA-2026-2690","OESA-2026-2691","OESA-2026-2692","OESA-2026-2693","UBUNTU-CVE-2026-6691"],"status":"published","title":"MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","severity":{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00126,"percentile":0.02325,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-120","CWE-787"],"published":"2026-05-06T15:08:23Z","modified":"2026-10-28T02:30:59Z","fixes":[{"ecosystem":"Debian:12","package":"mongo-c-driver","fixed_in":["1.23.1-1+deb12u3"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"mongo-c-driver","fixed_in":["1.30.4-1+deb13u2"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"mongo-c-driver","fixed_in":["2.2.0-1"],"sources":["osv"]},{"ecosystem":"openEuler:22.03-LTS-SP4","package":"mongo-c-driver","fixed_in":["1.30.6-3.oe2203sp4"],"sources":["osv"]},{"ecosystem":"openEuler:24.03-LTS-SP1","package":"mongo-c-driver","fixed_in":["1.30.6-3.oe2403sp1"],"sources":["osv"]},{"ecosystem":"openEuler:24.03-LTS-SP3","package":"mongo-c-driver","fixed_in":["1.30.6-3.oe2403sp3"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.23.1-1+deb12u3"}]}],"versions":["1.23.1-1","1.23.1-1+deb12u1","1.23.1-1+deb12u2"]},{"source":"osv","ecosystem":"Debian:13","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.30.4-1+deb13u2"}]}],"versions":["1.30.4-1","1.30.4-1+deb13u1"]},{"source":"osv","ecosystem":"Debian:14","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.0-1"}]}],"versions":["1.30.4-1","2.0.2-1","2.1.0-1","2.1.1-1","2.1.2-1"]},{"source":"osv","ecosystem":"openEuler:22.03-LTS-SP4","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.30.6-3.oe2203sp4"}]}]},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP1","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.30.6-3.oe2403sp1"}]}]},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP3","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.30.6-3.oe2403sp3"}]}]},{"source":"osv","ecosystem":"openEuler:20.03-LTS-SP4","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.27.4-3.oe2003sp4"}]}],"bundled":2},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.15.0-1","1.15.1-1","1.15.2-1","1.16.0-1","1.16.1-1","1.16.1-1build1","1.16.1-1build2","1.16.1-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.18.0-1","1.19.1-1","1.19.2-1","1.20.0-1","1.20.0-1build1","1.20.1-1","1.21.0-1","1.21.0-1build1","1.21.0-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.24.3-1","1.24.4-1","1.25.1-1","1.25.2-1","1.25.4-1","1.26.0-1","1.26.0-1.1ubuntu1","1.26.0-1.1ubuntu2","1.26.0-1.1ubuntu2+esm1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"mongo-c-driver","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.30.2-1","1.30.4-1ubuntu1"]}],"products":[{"vendor":"mongodb","product":"c_driver"},{"vendor":"mongodb inc.","product":"mongodb c driver"}],"references":[{"url":"https://jira.mongodb.org/browse/CDRIVER-6134","tags":["Patch","Vendor Advisory","Issue Tracking","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6691","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-587q-94wg-2pfp"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6691.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-6691","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2690","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2691","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2692","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2693","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6231","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-6691","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-6691","tags":["report"]},{"url":"https://github.com/mongodb/mongo-c-driver/commit/b4984965877d559862e225beba09cb4e9d4a56a6","tags":["report"]},{"url":"https://github.com/mongodb/mongo-c-driver/commit/d9c26f49e75d3de746a690db9c81ff5b4f6e21b0","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-6691","title":"MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","status":"published","published":"2026-05-06T15:08:23.671Z","modified":"2026-05-07T03:55:47.41Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"},{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-120"],"updated_at":"2026-11-02T13:49:53.818886Z"}],"euvd":[{"id":"EUVD-2026-27838","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","status":"published","published":"2026-05-06T15:08:23Z","modified":"2026-05-07T03:55:47Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T19:05:15.738879Z"}],"ghsa":[{"id":"GHSA-587q-94wg-2pfp","title":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username...","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","status":"published","published":"2026-05-06T18:30:30Z","modified":"2026-06-18T18:35:17Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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":"high"},{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-120","CWE-787"],"updated_at":"2026-11-02T15:08:53.737891Z"}],"nvd":[{"id":"CVE-2026-6691","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","status":"published","published":"2026-05-06T16:16:11.483Z","modified":"2026-10-26T19:10:00.163Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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":"high","assessor":"secondary"},{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-120","CWE-787"],"updated_at":"2026-11-02T14:12:17.418622Z"}],"osv":[{"id":"CVE-2026-6691","title":"MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","status":"published","published":"2026-05-06T15:08:23.671Z","modified":"2026-10-28T02:30:59.148006046Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-120"],"updated_at":"2026-11-02T15:45:14.46177Z"},{"id":"DEBIAN-CVE-2026-6691","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","status":"published","published":"2026-05-06T16:16:11.483Z","modified":"2026-10-27T09:47:31.09710551Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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":"high"}],"updated_at":"2026-11-02T15:45:58.699079Z"},{"id":"OESA-2026-2690","title":"mongo-c-driver security update","description":"mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.\r\n\r\nSecurity Fix(es):\n\nThe MongoDB C Driver\u0026apos;s Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.(CVE-2026-6691)","status":"published","published":"2026-06-24T11:11:37Z","modified":"2026-08-18T01:20:05.78972404Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"OESA-2026-2691","title":"mongo-c-driver security update","description":"mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.\r\n\r\nSecurity Fix(es):\n\nThe MongoDB C Driver\u0026apos;s Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.(CVE-2026-6691)","status":"published","published":"2026-06-24T11:11:37Z","modified":"2026-08-18T01:20:05.773506728Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"OESA-2026-2692","title":"mongo-c-driver security update","description":"mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.\r\n\r\nSecurity Fix(es):\n\nThe MongoDB C Driver\u0026apos;s Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.(CVE-2026-6691)","status":"published","published":"2026-06-24T11:11:37Z","modified":"2026-08-18T01:20:05.690888653Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"OESA-2026-2693","title":"mongo-c-driver security update","description":"mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.\r\n\r\nSecurity Fix(es):\n\nThe bson_validate function may return early on specific inputs and incorrectly report success. This behavior could result in skipping validation for BSON data, allowing malformed or invalid UTF-8 sequences to bypass validation and be processed incorrectly. The issue may affect applications that rely on these functions to validate untrusted BSON data before further processing. This issue affects MongoDB C Driver versions prior to 1.30.5, MongoDB C Driver version 2.0.0 and MongoDB C Driver version 2.0.1.(CVE-2026-6231)\n\nThe MongoDB C Driver\u0026apos;s Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.(CVE-2026-6691)","status":"published","published":"2026-06-24T11:11:37Z","modified":"2026-08-18T01:20:05.473234473Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"UBUNTU-CVE-2026-6691","description":"The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.","status":"published","published":"2026-05-06T16:16:00Z","modified":"2026-05-14T14:55:08.035087Z","cvss":[{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"},{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T16:56:53.710209Z"}]}}