{"id":"GHSA-52xf-5p2m-9wrv","aliases":[],"status":"published","title":"s2n-tls has a potentially observable differences in RSA premaster secret handling","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].\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: \u003c= 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","facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-203"],"published":"2024-06-06T14:26:18Z","modified":"2026-09-10T03:50:14Z","fixes":[{"ecosystem":"crates.io","package":"s2n-tls","fixed_in":["0.2.7"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"crates.io","package":"s2n-tls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.2.6"},{"fixed":"0.2.7"}]}]},{"source":"osv","ecosystem":"crates.io","package":"s2n-tls","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.2.7"}]}]}],"references":[{"url":"https://github.com/aws/s2n-tls/security/advisories/GHSA-52xf-5p2m-9wrv","tags":["web"]},{"url":"https://github.com/aws/s2n-tls/commit/114ccab0ff2cde491203ac841837d0d39b767412","tags":["web"]},{"url":"https://github.com/aws/s2n-tls/releases/tag/v1.4.16","tags":["web"]},{"url":"https://github.com/advisories/GHSA-52xf-5p2m-9wrv"},{"url":"https://github.com/aws/s2n-tls","tags":["package"]}],"sources":{"ghsa":[{"id":"GHSA-52xf-5p2m-9wrv","title":"s2n-tls has a potentially observable differences in RSA premaster secret handling","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].\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: \u003c= 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","status":"published","published":"2024-06-06T14:26:18Z","modified":"2024-06-06T14:26:27Z","cwes":["CWE-203"],"updated_at":"2026-11-02T14:37:53.703286Z"}],"osv":[{"id":"GHSA-52xf-5p2m-9wrv","title":"s2n-tls has a potentially observable differences in RSA premaster secret handling","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].\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: \u003c= 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","status":"published","published":"2024-06-06T14:26:18Z","modified":"2026-09-10T03:50:14.957372584Z","cwes":["CWE-203"],"updated_at":"2026-11-02T15:46:37.864461Z"}]}}