{"id":"UBUNTU-CVE-2026-69249","details":"python-cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In versions 42.0.0 through 48.0.0, when resolving invalid certificate chains that include duplicate copies of self-signed certificates, the processing recursively invokes the same candidate, leading to an exponential blowup. Although the limitation that the chain depth cannot exceed a specified maximum depth prevents unbounded recursion and guarantees termination, an attacker-controlled certificate chain can lead the processing to easily take more than 5s to reject in testing. This amplification could form the basis for a resource exhaustion denial of service attack. The core issue arises in the recursive nature of build_chain_inner, which does not de-duplicate against previously analyzed candidates. As the correctness of validation is not affected, the integrity of a system cannot be compromised through this vector, only its availability. This issue is fixed in 49.0.0.","modified":"2026-09-17T19:54:57.302106748Z","published":"2026-08-03T22:16:00Z","related":["USN-8776-1"],"upstream":["CVE-2026-69249"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-69249"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-69249"},{"type":"REPORT","url":"https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww"},{"type":"REPORT","url":"https://github.com/pyca/cryptography/pull/14960"},{"type":"REPORT","url":"https://github.com/pyca/cryptography/commit/4a12cf49675a184e47f912b00b04f3a629283582"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8776-1"}],"affected":[{"package":{"name":"python-cryptography","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/python-cryptography?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"46.0.5-1ubuntu2.2"}]}],"versions":["43.0.0-1ubuntu1","46.0.1-1ubuntu2","46.0.5-1ubuntu1","46.0.5-1ubuntu2"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"46.0.5-1ubuntu2.2","binary_name":"python3-cryptography"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-69249.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}