{"id":"GHSA-52xf-5p2m-9wrv","aliases":[],"url":"https://o3.security/vulnerability/GHSA-52xf-5p2m-9wrv","summary":"s2n-tls has a potentially observable differences in RSA premaster secret handling","details":"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].\n\nWe would like to thank Hubert Kario [2] for reporting this issue.\n\n\n### Impact\n\nThe extent of this issue is a timing difference. No practical attack on s2n-tls has been demonstrated.\n\nThis 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.\n\nImpacted versions: <= v1.4.15.\n\n\n### Patches\n\nThe patch is included in v1.4.16 [3].\n\n### Workarounds\n\nApplications can work around this issue by using an s2n-tls security policy that disallows RSA key exchange.\n\nIf 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 [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue.\n\n[1] https://people.redhat.com/~hkario/marvin/\n[2] https://github.com/tomato42\n[3] https://github.com/aws/s2n-tls/releases/tag/v1.4.16\n[4] https://aws.amazon.com/security/vulnerability-reporting","published":"2024-06-06T14:26:18Z","modified":"2026-09-10T03:50:14.957372584Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"s2n-tls","fixedVersion":"0.2.7"}],"fix":{"url":"https://github.com/aws/s2n-tls/commit/114ccab0ff2cde491203ac841837d0d39b767412","label":"aws/s2n-tls@114ccab"},"references":[{"type":"WEB","url":"https://github.com/aws/s2n-tls/security/advisories/GHSA-52xf-5p2m-9wrv"},{"type":"WEB","url":"https://github.com/aws/s2n-tls/commit/114ccab0ff2cde491203ac841837d0d39b767412"},{"type":"PACKAGE","url":"https://github.com/aws/s2n-tls"},{"type":"WEB","url":"https://github.com/aws/s2n-tls/releases/tag/v1.4.16"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-10T03:50:14.957372584Z"}}