{"id":"CVE-2026-69249","state":"PUBLISHED","title":"python-cryptography: Duplicate self-signed intermediates can cause exponential path-building","description":"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.","publishedAt":"2026-08-03T21:26:45.826Z","updatedAt":"2026-09-04T21:20:32.666Z","severity":{"score":8.7,"label":"High","version":"4.0","vector":"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","source":"GitHub_M"},"assigner":"GitHub_M","products":["pyca cryptography"],"affected":[{"vendor":"pyca","product":"cryptography","versions":[{"version":">= 42.0.0, < 49.0.0","status":"affected"}]}],"references":["https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww","https://github.com/pyca/cryptography/pull/14960","https://github.com/pyca/cryptography/commit/3763aa79b","https://github.com/pyca/cryptography/commit/4a12cf49675a184e47f912b00b04f3a629283582","https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3553.yaml"],"weaknesses":["CWE-400"],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/69xxx/CVE-2026-69249.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-69249","state":"PUBLISHED","datePublished":"2026-08-03T21:26:45.826Z","dateUpdated":"2026-09-04T21:20:32.666Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-03T19:54:19.852Z"},"containers":{"cna":{"title":"python-cryptography: Duplicate self-signed intermediates can cause exponential path-building","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"pyca","product":"cryptography","versions":[{"version":">= 42.0.0, < 49.0.0","status":"affected"}]}],"references":[{"url":"https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww","name":"https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/pyca/cryptography/pull/14960","name":"https://github.com/pyca/cryptography/pull/14960","tags":["x_refsource_MISC"]},{"url":"https://github.com/pyca/cryptography/commit/3763aa79b","name":"https://github.com/pyca/cryptography/commit/3763aa79b","tags":["x_refsource_MISC"]},{"url":"https://github.com/pyca/cryptography/commit/4a12cf49675a184e47f912b00b04f3a629283582","name":"https://github.com/pyca/cryptography/commit/4a12cf49675a184e47f912b00b04f3a629283582","tags":["x_refsource_MISC"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3553.yaml","name":"https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3553.yaml","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.7,"baseSeverity":"HIGH","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-04T21:20:32.666Z"},"source":{"advisory":"GHSA-jwv3-5hgf-82ww","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-04T14:08:23.254769Z","id":"CVE-2026-69249","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-04T14:08:58.056Z"}}]}}}