{"id":"CVE-2026-16318","aliases":["EUVD-2026-46402","GHSA-cr7x-863j-xrc7","SUSE-SU-2026:5101-1","openSUSE-SU-2026:11492-1","openSUSE-SU-2026:11526-1","openSUSE-SU-2026:21474-1","openSUSE-SU-2026:21501-1"],"status":"published","title":"QUIC Transport Parameters Memory Leak During HelloRetryRequest in s2n-tls","description":"The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2n_alloc instead of s2n_realloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice on the same connection. On the second call, s2n_alloc zeroes the existing pointer before allocating new memory, causing the first allocation to be leaked.\n\n\n\nThis can occur during normal QUIC traffic when a client offers a key share group the server does not prefer. An unauthenticated user can amplify the issue by deliberately forcing HelloRetryRequests, causing up to approximately 64 KB of unreachable memory per handshake. Over time, this can lead to increased memory consumption on long-running server processes. The unreachable memory is only reclaimed when the process is restarted.\n\n\n\nOnly server-side QUIC-enabled deployments are affected. Non-QUIC TLS connections are not affected.\n\n\n\nWe recommend you upgrade s2n-tls to version v1.7.6","severity":{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00388,"percentile":0.33412,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-401"],"published":"2026-07-21T20:14:02Z","modified":"2026-11-05T13:27:13Z","affected":[{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Public Cloud 15 SP6","package":"aws-efs-utils","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.3.4-150600.17.12.1"}]}],"bundled":3},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Public Cloud 15 SP7","package":"aws-efs-utils","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.3.4-150600.17.12.1"}]}],"bundled":3},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"aws-efs-utils","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.0-1.1"}]}],"bundled":3},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"s2n","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.7.7-1.1"}]}],"bundled":2},{"source":"osv","ecosystem":"openSUSE:Leap 16.0","package":"s2n","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.5.1-bp160.2.1"}]}],"bundled":2}],"products":[{"vendor":"amazon","product":"s2n-tls"},{"vendor":"aws","product":"s2n-tls"}],"references":[{"url":"https://github.com/aws/s2n-tls/releases/tag/v1.7.6","tags":["release-notes","patch","fix"]},{"url":"https://staging.prod.website.marketing.aws.dev/security/security-bulletins/2026-062-aws/","tags":["vendor-advisory","advisory"]},{"url":"https://github.com/aws/s2n-tls/security/advisories/GHSA-cr7x-863j-xrc7","tags":["release-notes","advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/16xxx/CVE-2026-16318.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-16318","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-20265101-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1263683","tags":["report"]},{"url":"https://bugzilla.suse.com/1272349","tags":["report"]},{"url":"https://bugzilla.suse.com/1272354","tags":["report"]},{"url":"https://bugzilla.suse.com/1274202","tags":["report"]},{"url":"https://bugzilla.suse.com/1275449","tags":["report"]},{"url":"https://bugzilla.suse.com/1275450","tags":["report"]},{"url":"https://bugzilla.suse.com/1281947","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2026-16317","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-16318","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-25541","tags":["web"]},{"url":"","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1272352","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-16318","title":"QUIC Transport Parameters Memory Leak During HelloRetryRequest in s2n-tls","description":"The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2n_alloc instead of s2n_realloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice on the same connection. On the second call, s2n_alloc zeroes the existing pointer before allocating new memory, causing the first allocation to be leaked.\n\n\n\nThis can occur during normal QUIC traffic when a client offers a key share group the server does not prefer. An unauthenticated user can amplify the issue by deliberately forcing HelloRetryRequests, causing up to approximately 64 KB of unreachable memory per handshake. Over time, this can lead to increased memory consumption on long-running server processes. The unreachable memory is only reclaimed when the process is restarted.\n\n\n\nOnly server-side QUIC-enabled deployments are affected. Non-QUIC TLS connections are not affected.\n\n\n\nWe recommend you upgrade s2n-tls to version v1.7.6","status":"published","published":"2026-07-21T20:14:02.363Z","modified":"2026-07-22T19:41:13.27Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-401"],"updated_at":"2026-11-02T14:20:10.870108Z"}],"euvd":[{"id":"EUVD-2026-46402","description":"The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2n_alloc instead of s2n_realloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice on the same connection. On the second call, s2n_alloc zeroes the existing pointer before allocating new memory, causing the first allocation to be leaked.\n\n\n\nThis can occur during normal QUIC traffic when a client offers a key share group the server does not prefer. An unauthenticated user can amplify the issue by deliberately forcing HelloRetryRequests, causing up to approximately 64 KB of unreachable memory per handshake. Over time, this can lead to increased memory consumption on long-running server processes. The unreachable memory is only reclaimed when the process is restarted.\n\n\n\nOnly server-side QUIC-enabled deployments are affected. Non-QUIC TLS connections are not affected.\n\n\n\nWe recommend you upgrade s2n-tls to version v1.7.6","status":"published","published":"2026-07-21T20:14:02Z","modified":"2026-07-22T19:41:13Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T18:19:44.433437Z"}],"nvd":[{"id":"CVE-2026-16318","description":"The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2n_alloc instead of s2n_realloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice on the same connection. On the second call, s2n_alloc zeroes the existing pointer before allocating new memory, causing the first allocation to be leaked.\n\n\n\nThis can occur during normal QUIC traffic when a client offers a key share group the server does not prefer. An unauthenticated user can amplify the issue by deliberately forcing HelloRetryRequests, causing up to approximately 64 KB of unreachable memory per handshake. Over time, this can lead to increased memory consumption on long-running server processes. The unreachable memory is only reclaimed when the process is restarted.\n\n\n\nOnly server-side QUIC-enabled deployments are affected. Non-QUIC TLS connections are not affected.\n\n\n\nWe recommend you upgrade s2n-tls to version v1.7.6","status":"published","published":"2026-07-21T21:16:49.22Z","modified":"2026-10-24T19:10:00.127Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"secondary"}],"cwes":["CWE-401"],"updated_at":"2026-11-02T14:12:31.394335Z"}],"osv":[{"id":"CVE-2026-16318","title":"QUIC Transport Parameters Memory Leak During HelloRetryRequest in s2n-tls","description":"The QUIC transport parameters extension handler in s2n-tls incorrectly uses s2n_alloc instead of s2n_realloc to store the peer's transport parameters. When a TLS 1.3 connection goes through a HelloRetryRequest, the handler is called twice on the same connection. On the second call, s2n_alloc zeroes the existing pointer before allocating new memory, causing the first allocation to be leaked.\n\n\n\nThis can occur during normal QUIC traffic when a client offers a key share group the server does not prefer. An unauthenticated user can amplify the issue by deliberately forcing HelloRetryRequests, causing up to approximately 64 KB of unreachable memory per handshake. Over time, this can lead to increased memory consumption on long-running server processes. The unreachable memory is only reclaimed when the process is restarted.\n\n\n\nOnly server-side QUIC-enabled deployments are affected. Non-QUIC TLS connections are not affected.\n\n\n\nWe recommend you upgrade s2n-tls to version v1.7.6","status":"published","published":"2026-07-21T20:14:02.363Z","modified":"2026-11-05T13:27:13.893701493Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-401"],"updated_at":"2026-11-05T16:37:45.64821Z"},{"id":"openSUSE-SU-2026:11492-1","title":"aws-efs-utils-3.2.0-1.1 on GA media","description":"These are all security issues fixed in the aws-efs-utils-3.2.0-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-08-11T00:00:00Z","modified":"2026-08-12T10:45:07.13203099Z","updated_at":"2026-11-02T16:58:39.516824Z"},{"id":"openSUSE-SU-2026:11526-1","title":"libs2n1-1.7.7-1.1 on GA media","description":"These are all security issues fixed in the libs2n1-1.7.7-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-08-15T00:00:00Z","modified":"2026-08-16T11:45:05.557675656Z","updated_at":"2026-11-02T16:58:39.516824Z"},{"id":"openSUSE-SU-2026:21474-1","title":"Security update for s2n","description":"This update for s2n fixes the following issues:\n\nChanges in s2n:\n\n- CVE-2026-16318: Denial of Service due to memory leak in QUIC\n  transport parameters handler (bsc#1272352)\n- CVE-2026-16317: man-in-the-middle attack can silently discard\n  individual application data records\n","status":"withdrawn","published":"2026-07-28T15:14:50Z","modified":"2026-07-31T14:01:33.622023341Z","updated_at":"2026-11-02T16:58:41.885092Z"},{"id":"openSUSE-SU-2026:21501-1","title":"Security update for s2n","description":"This update for s2n fixes the following issues:\n\nChanges in s2n:\n\n- CVE-2026-16318: Denial of Service due to memory leak in QUIC\n  transport parameters handler (bsc#1272352)\n- CVE-2026-16317: man-in-the-middle attack can silently discard\n  individual application data records\n","status":"published","published":"2026-07-29T09:24:11Z","modified":"2026-07-31T18:24:09.693637563Z","updated_at":"2026-11-02T16:58:41.885092Z"},{"id":"SUSE-SU-2026:5101-1","title":"Security update for aws-efs-utils","description":"This update for aws-efs-utils fixes the following issues:\n\nSecurity issues fixed:\n\n- CVE-2026-16317: s2n-tls: man-in-the-middle attack can silently discard individual application data records\n  (bsc#1272354).\n- CVE-2026-16318: s2n-tls: Denial of Service due to memory leak in QUIC transport parameters handler (bsc#1272349).\n- CVE-2026-25541: bytes: integer overflow in 'BytesMut:reserve' can lead to undefined behavior and crashes\n  (bsc#1274202).\n\nChanges for aws-efs-utils:\n\n- Update to version 3.3.4\n","status":"published","published":"2026-11-04T18:01:29Z","modified":"2026-11-05T13:15:07.550193736Z","updated_at":"2026-11-05T13:30:00.949926Z"}]}}