{"cve":"CVE-2026-69249","nvd":{"published":"2026-08-03T22:16:52.720","modified":"2026-10-23T21:10:00.157","status":"Awaiting Analysis","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.","cvss_v4":{"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","score":8.7},"cvss_v3":null,"cwes":["CWE-400"],"references":["https://github.com/pyca/cryptography/commit/3763aa79b","https://github.com/pyca/cryptography/commit/4a12cf49675a184e47f912b00b04f3a629283582","https://github.com/pyca/cryptography/pull/14960","https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww","https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3553.yaml"],"products":[],"source":"nvd","synced_at":"2026-10-24T16:53:34.184483516+00:00"},"epss":{"cve":"CVE-2026-69249","score":0.00262,"percentile":0.17785,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-jwv3-5hgf-82ww","url":"https://osv.dev/vulnerability/GHSA-jwv3-5hgf-82ww","summary":"python-cryptography: Duplicate self-signed intermediates can cause exponential path-building","modified":"2026-09-24T14:45:10.238420831Z","packages":[{"ecosystem":"PyPI","name":"cryptography","purl":"pkg:pypi/cryptography","ranges":[">=42.0.0 <49.0.0"],"fixed":["49.0.0"]}]},{"id":"PYSEC-2026-3553","url":"https://osv.dev/vulnerability/PYSEC-2026-3553","summary":"python-cryptography: Duplicate self-signed intermediates can cause exponential path-building","modified":"2026-08-04T14:30:26.222821809Z","packages":[{"ecosystem":"PyPI","name":"cryptography","purl":"pkg:pypi/cryptography","ranges":["<49.0.0"],"fixed":["49.0.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}