Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The cryptography package for Python, versions 42.0.0 up to but not including 49.0.0, is vulnerable to a denial of service when building certificate chains. Duplicate copies of self-signed certificates can trigger exponential path-building, so an attacker who supplies a crafted certificate chain could make validation take more than 5 seconds, which can exhaust resources. Validation correctness is not affected. Upgrade to version 49.0.0. The source gives no workaround.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 8.7 | High | 4.0 | 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 | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0026, the 18th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Jul 2026, 12:17 UTC Published by the maintainers as a GitHub repository advisory
- 31 Oct 2026, 14:09 UTC First seen by agentprime
- 31 Oct 2026, 14:09 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-jwv3-5hgf-82ww
- OSV: GHSA-jwv3-5hgf-82ww
- github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww
- nvd.nist.gov/vuln/detail/CVE-2026-69249
- github.com/pyca/cryptography/pull/14960
- github.com/pyca/cryptography/commit/3763aa79b
- github.com/pyca/cryptography/commit/4a12cf49675a184e47f912b00b04f3a629283582
- github.com/pyca/cryptography
- github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3553.yaml