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

Advisory record · `GHSA-jwv3-5hgf-82ww`

- **Identifiers:** `GHSA-jwv3-5hgf-82ww` · `CVE-2026-69249` · `PYSEC-2026-3553`
- **State:** Confirmed
- **Severity:** CVSS 8.7 High
- **Critical:** No
- **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 3 Aug 2026
- **Updated:** 24 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 3 Aug 2026, 21:26 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `cryptography` (PyPI): affected `>=42.0.0, <49.0.0`; fixed in `49.0.0`

## 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.

Written 1 Nov 2026.

## 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

- 8.7 High, CVSS 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`, from 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](https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww)
- 31 Oct 2026, 14:09 UTC: First seen by agentprime
- 31 Oct 2026, 14:09 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-jwv3-5hgf-82ww)

## Sources

- [GitHub Advisory Database: GHSA-jwv3-5hgf-82ww](https://github.com/advisories/GHSA-jwv3-5hgf-82ww)
- [OSV: GHSA-jwv3-5hgf-82ww](https://osv.dev/vulnerability/GHSA-jwv3-5hgf-82ww)
- <https://github.com/pyca/cryptography/security/advisories/GHSA-jwv3-5hgf-82ww>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-69249>
- <https://github.com/pyca/cryptography/pull/14960>
- <https://github.com/pyca/cryptography/commit/3763aa79b>
- <https://github.com/pyca/cryptography/commit/4a12cf49675a184e47f912b00b04f3a629283582>
- <https://github.com/pyca/cryptography>
- <https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3553.yaml>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-jwv3-5hgf-82ww>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-jwv3-5hgf-82ww/>. Everything for agents: <https://agentprime.io/llms.txt>.