{"id":"UBUNTU-CVE-2026-6691","details":"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.","modified":"2026-05-14T14:55:08.035087Z","published":"2026-05-06T16:16:00Z","upstream":["CVE-2026-6691"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-6691"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-6691"},{"type":"REPORT","url":"https://jira.mongodb.org/browse/CDRIVER-6134"},{"type":"REPORT","url":"https://github.com/mongodb/mongo-c-driver/commit/b4984965877d559862e225beba09cb4e9d4a56a6"},{"type":"REPORT","url":"https://github.com/mongodb/mongo-c-driver/commit/d9c26f49e75d3de746a690db9c81ff5b4f6e21b0"}],"affected":[{"package":{"name":"mongo-c-driver","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/mongo-c-driver@1.16.1-1ubuntu0.1~esm1?arch=source&distro=esm-apps/focal"},"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"],"ecosystem_specific":{"binaries":[{"binary_name":"libbson-1.0-0","binary_version":"1.16.1-1ubuntu0.1~esm1"},{"binary_name":"libmongoc-1.0-0","binary_version":"1.16.1-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6691.json"}},{"package":{"name":"mongo-c-driver","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/mongo-c-driver@1.21.0-1ubuntu0.1~esm1?arch=source&distro=esm-apps/jammy"},"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"],"ecosystem_specific":{"binaries":[{"binary_name":"libbson-1.0-0","binary_version":"1.21.0-1ubuntu0.1~esm1"},{"binary_name":"libmongoc-1.0-0","binary_version":"1.21.0-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6691.json"}},{"package":{"name":"mongo-c-driver","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/mongo-c-driver@1.26.0-1.1ubuntu2+esm1?arch=source&distro=esm-apps/noble"},"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"],"ecosystem_specific":{"binaries":[{"binary_name":"libbson-1.0-0t64","binary_version":"1.26.0-1.1ubuntu2+esm1"},{"binary_name":"libmongoc-1.0-0t64","binary_version":"1.26.0-1.1ubuntu2+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6691.json"}},{"package":{"name":"mongo-c-driver","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/mongo-c-driver@1.30.4-1ubuntu1?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.30.2-1","1.30.4-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.30.4-1ubuntu1","binary_name":"libbson-1.0-0t64"},{"binary_name":"libmongoc-1.0-0t64","binary_version":"1.30.4-1ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6691.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},{"type":"CVSS_V4","score":"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"},{"type":"Ubuntu","score":"medium"}]}