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Not in CISA KEV

CVE-2026-69249 — cryptography

Fix: pyca/cryptography@3763aa7

CVE-2026-69249 is a Uncontrolled Resource Consumption vulnerability in cryptography. A fix is available for cryptography — see the affected versions and patch details below.

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

Also known asGHSA-jwv3-5hgf-82wwPYSEC-2026-3553
Published
Aug 3, 2026
Updated
Sep 12, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 18, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-69249.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs17th percentile — riskier than 17% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected
🐍cryptography

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIcryptography≥ 42.0.0&&< 49.0.049.0.0pip install --upgrade 'cryptography==49.0.0'

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cryptography, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update cryptography to 49.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-69249 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-69249 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-69249. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

Red Hat rates this Important (CVSS 3.1 7.5). Duplicate self-signed intermediates can make PolicyBuilder path-building take seconds per request. GitHub CNA CVSS 4.0 is 8.7.

ProductFixed inAdvisory
Red Hat Enterprise Linux 10python3.14-cryptography-0:45.0.4-4.el10_2.5RHSA-2026:64795
Red Hat Enterprise Linux 9python3.14-cryptography-0:45.0.4-4.el9_8.6RHSA-2026:64774
Red Hat Hardened Imagespython-cryptography-main-50.0.0-1.hum1RHSA-2026:55543
Ubuntu
USN-8776-1Ubuntu

Frequently Asked Questions

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 am
O3 Security · Impact-Aware SCA

Is CVE-2026-69249 in your dependencies?

O3 Security finds CVE-2026-69249 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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CVE-2026-69249: cryptography DoS | O3 Security