Python Cryptography package vulnerable to Bleichenbacher timing oracle attackGHSA-3ww4-gg4f-jr7f
HIGHGHSA-3ww4-gg4f-jr7f is a high-severity (CVSS 7.5) CWE-203 vulnerability in cryptography. A fix is available for cryptography — see the affected versions and patch details below.
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.
Exploitation and automatability from CISA’s SSVC triage for GHSA-3ww4-gg4f-jr7f.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
cryptographyReal-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
A flaw was found in the python-cryptography package. This issue may allow a remote attacker to decrypt captured messages in TLS servers that use RSA key exchanges, which may lead to exposure of confidential or sensitive data.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | cryptography | all versions | 42.0.0pip install --upgrade 'cryptography==42.0.0' |
Affected Products
couchbase servercouchbasecryptographycryptography.ioansible automation platformredhatenterprise linuxredhatupdate infrastructureredhatDetection & mitigation playbook
Open-source dependencyDetect
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.
Fix
Update cryptography to 42.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3ww4-gg4f-jr7f is resolved across your whole dependency graph.
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.
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.
This vulnerability exists due to an incomplete fix for CVE-2020-25659. The CVE-2020-25659 vulnerability presents a moderate severity concern due to its specific impact on applications utilizing RSA decryption with PKCS#1 v1.5 padding. While the vulnerability could potentially lead to leakage in RSA decryption…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-3ww4-gg4f-jr7f (CC BY 4.0)
Frequently Asked Questions
Is GHSA-3ww4-gg4f-jr7f in your dependencies?
Find it across PyPI, including transitive dependencies.