CVE-2020-25659 is a medium-severity (CVSS 5.9) CWE-385 vulnerability in cryptography. A fix is available for cryptography — see the affected versions and patch details below.
RSA decryption vulnerable to Bleichenbacher timing vulnerability
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2020-25659 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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
RSA decryption was vulnerable to Bleichenbacher timing vulnerabilities, which would impact people using RSA decryption in online scenarios. This is fixed in cryptography 3.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | cryptography | all versions | 3.2pip install --upgrade 'cryptography==3.2' |
Affected Products
cryptographycryptography.iocommunications cloud native core network function cloud native environmentoracleDetection & 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 3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-25659 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.
In Red Hat OpenStack Platform, because the flaw has a lower impact and the fix would require a substantial amount of development, no update will be provided at this time for the RHOSP python-cryptography package.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | python-cryptography-0:3.2.1-4.el8 | RHSA-2021:1608 |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | rh-python38-babel-0:2.7.0-12.el7 | RHSA-2021:3254 |
| Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 | redhat-virtualization-host-0:4.4.6-20210527.3.el8_4 | RHSA-2021:2239 |
Frequently Asked Questions
Is CVE-2020-25659 in your dependencies?
Find it across PyPI, including transitive dependencies.