python-cryptography: Duplicate self-signed intermediates can cause exponential path-building

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · 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 source

EPSS

• CVE-2026-69249: 0.26% estimated exploitation activity in the next 30 days; percentile 18.02 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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. This work was completed by Trail of Bits as part of the Patch The Planet project in collaboration with OpenAI. The finding was identified primarily by the Codex coding agent, and manually reviewed before submission. Details The core issue arises in the recursive nature of buildchaininner, which does not de-duplicate against previously analyzed candidates. A sufficient patch is to track valid issuers, and to skip seen ones before recursing. By…

Published by the source

3 Aug 2026, 21:26 UTC

Last modified by the source

24 Sep 2026, 14:35 UTC

Source last checked

26 Oct 2026, 13:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-jwv3-5hgf-82ww

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# Patch Next advisory brief: CVE-2026-69249

Advisory: python-cryptography: Duplicate self-signed intermediates can cause exponential path-building
IDs: CVE-2026-69249, GHSA-jwv3-5hgf-82ww
Record: https://patchnext.com/advisories/cve-2026-69249 (revision 1, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: cryptography 49.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI cryptography: affected >= 42.0.0, < 49.0.0; fixed in 49.0.0

## Suggested inspection (read-only)
- `python -m pip show cryptography`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on cryptography.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-jwv3-5hgf-82ww (GitHub-reviewed advisory GHSA-jwv3-5hgf-82ww lists affected ranges: PyPI cryptography >=42.0.0 <49.0.0)

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