GHSA-52xf-5p2m-9wrv — s2n-tls
Fix: aws/s2n-tls@114ccabGHSA-52xf-5p2m-9wrv is a security vulnerability in s2n-tls. A fix is available for s2n-tls — see the affected versions and patch details below.
s2n-tls has a potentially observable differences in RSA premaster secret handling
Real-World Exposure
s2n-tlsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
When receiving a message from a client that sent an invalid RSA premaster secret, an issue in s2n-tls results in the server performing additional processing when the premaster secret contains an incorrect client hello version. While no practical attack on s2n-tls has been demonstrated, this causes a small timing difference which could theoretically be used as described in the Marvin Attack [1].
We would like to thank Hubert Kario [2] for reporting this issue.
Impact
The extent of this issue is a timing difference. No practical attack on s2n-tls has been demonstrated.
This issue affects server applications that permit RSA key exchange. Applications that use the default, built-in blinding feature or properly implement self-service blinding are not affected.
Impacted versions: <= v1.4.15.
Patches
The patch is included in v1.4.16 [3].
Workarounds
Applications can work around this issue by using an s2n-tls security policy that disallows RSA key exchange.
If you have any questions or comments about this advisory we ask that you contact AWS/Amazon Security via our vulnerability reporting page [4] or directly via email to [email protected]. Please do not create a public GitHub issue.
[1] https://people.redhat.com/~hkario/marvin/ [2] https://github.com/tomato42 [3] https://github.com/aws/s2n-tls/releases/tag/v1.4.16 [4] https://aws.amazon.com/security/vulnerability-reporting
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | s2n-tls | all versions | 0.2.7cargo update -p s2n-tls --precise 0.2.7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for s2n-tls, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update s2n-tls to 0.2.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-52xf-5p2m-9wrv 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-52xf-5p2m-9wrv can be triaged on real exposure rather than presence alone.
Tailored to GHSA-52xf-5p2m-9wrv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-52xf-5p2m-9wrv in your dependencies?
O3 Security finds GHSA-52xf-5p2m-9wrv across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.