{"id":"UBUNTU-CVE-2026-107161","details":"A heap-based buffer overflow flaw was found in Cyrus SASL. The add_to_challenge() function in the DIGEST-MD5 plugin computes the size of the buffer needed for a challenge/response field before DIGEST-MD5 quoting is applied, but does not recompute that size when quoting (escaping special characters) makes the value longer. The under-sized buffer is then passed to strcat(), causing a heap-based out-of-bounds write whose size depends on attacker-controlled input. A malicious or on-path DIGEST-MD5 (or HTTP Digest) server can trigger this flaw in a connecting client by supplying a crafted challenge field, such as realm or nonce, most likely resulting in a crash of the client application.","modified":"2026-10-08T19:47:01.188609053Z","published":"2026-10-08T00:00:00Z","upstream":["CVE-2026-107161"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-107161"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-107161"},{"type":"REPORT","url":"https://github.com/cyrusimap/cyrus-sasl/issues/889"},{"type":"REPORT","url":"https://github.com/cyrusimap/cyrus-sasl/pull/892"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2460420"},{"type":"REPORT","url":"https://access.redhat.com/security/cve/CVE-2026-107161"}],"affected":[{"package":{"name":"cyrus-sasl2","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/cyrus-sasl2?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.25.dfsg1-17","2.1.25.dfsg1-17build1","2.1.25.dfsg1-17ubuntu0.1~esm1","2.1.25.dfsg1-17ubuntu0.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"libsasl2-2","binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2"},{"binary_name":"libsasl2-modules","binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2"},{"binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2","binary_name":"libsasl2-modules-db"},{"binary_name":"libsasl2-modules-gssapi-heimdal","binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2"},{"binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2","binary_name":"libsasl2-modules-gssapi-mit"},{"binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2","binary_name":"libsasl2-modules-ldap"},{"binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2","binary_name":"libsasl2-modules-otp"},{"binary_name":"libsasl2-modules-sql","binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2"},{"binary_name":"sasl2-bin","binary_version":"2.1.25.dfsg1-17ubuntu0.1~esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-107161.json"}},{"package":{"name":"cyrus-sasl2","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/cyrus-sasl2?arch=source&distro=esm-infra%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.26.dfsg1-14","2.1.26.dfsg1-14build1","2.1.26.dfsg1-14ubuntu0.1","2.1.26.dfsg1-14ubuntu0.2","2.1.26.dfsg1-14ubuntu0.2+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libsasl2-2","binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1"},{"binary_name":"libsasl2-modules","binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1"},{"binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1","binary_name":"libsasl2-modules-db"},{"binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1","binary_name":"libsasl2-modules-gssapi-heimdal"},{"binary_name":"libsasl2-modules-gssapi-mit","binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1"},{"binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1","binary_name":"libsasl2-modules-ldap"},{"binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1","binary_name":"libsasl2-modules-otp"},{"binary_name":"libsasl2-modules-sql","binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1"},{"binary_name":"sasl2-bin","binary_version":"2.1.26.dfsg1-14ubuntu0.2+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-107161.json"}},{"package":{"name":"cyrus-sasl2","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/cyrus-sasl2?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.27~101-g0780600+dfsg-3ubuntu1","2.1.27~101-g0780600+dfsg-3ubuntu2","2.1.27~101-g0780600+dfsg-3ubuntu2.1","2.1.27~101-g0780600+dfsg-3ubuntu2.3","2.1.27~101-g0780600+dfsg-3ubuntu2.4"],"ecosystem_specific":{"binaries":[{"binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4","binary_name":"libsasl2-2"},{"binary_name":"libsasl2-modules","binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4"},{"binary_name":"libsasl2-modules-db","binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4"},{"binary_name":"libsasl2-modules-gssapi-heimdal","binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4"},{"binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4","binary_name":"libsasl2-modules-gssapi-mit"},{"binary_name":"libsasl2-modules-ldap","binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4"},{"binary_name":"libsasl2-modules-otp","binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4"},{"binary_name":"libsasl2-modules-sql","binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4"},{"binary_name":"sasl2-bin","binary_version":"2.1.27~101-g0780600+dfsg-3ubuntu2.4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-107161.json"}},{"package":{"name":"cyrus-sasl2","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/cyrus-sasl2?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.27+dfsg-1build3","2.1.27+dfsg-2","2.1.27+dfsg-2ubuntu0.1"],"ecosystem_specific":{"binaries":[{"binary_name":"libsasl2-2","binary_version":"2.1.27+dfsg-2ubuntu0.1"},{"binary_name":"libsasl2-mod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