{"id":"CVE-2026-99139","aliases":[],"title":"tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)","titleSource":"Linux","descriptionSource":"Linux","products":[{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2","status":"affected","lessThan":"c1804ef016392dd91267d2207ee43b1de34302ca","versionType":"git"},{"version":"0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2","status":"affected","lessThan":"a8e45471afa230c1431c26c8e99ec24377e3b514","versionType":"git"},{"version":"0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2","status":"affected","lessThan":"5271b79b7ad68dcb222e893773f92bdabf7750f3","versionType":"git"}],"defaultStatus":"unaffected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99139"},{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"5.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.6","versionType":"semver"},{"version":"6.18.59","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"defaultStatus":"affected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99139"}],"remediation":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)\n\ndo_tcp_getsockopt() reads icsk->icsk_ca_ops->name without holding\nrcu_read_lock(). Since commit 0baf26b0fcd7 (\"bpf: tcp: Support\ntcp_congestion_ops in bpf\"), icsk_ca_ops can point to dynamically\nallocated BPF struct_ops memory that may be freed concurrently via\nsetsockopt(TCP_CONGESTION), leading to a use-after-free.\n\n  BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60\n  Read of size 16 at addr ffff888013505260 by task exploit/149\n   _copy_to_user+0x37/0x60\n   do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585)\n   tcp_getsockopt+0x91/0xf0\n   __sys_getsockopt+0xf7/0x170\n\nFix this by holding rcu_read_lock() around the ca_ops->name access,\nusing READ_ONCE() to load icsk_ca_ops, and copying the name to a\nstack buffer before releasing the lock. Also annotate the relevant\nicsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN\ndata-race issue.","severity":"unknown","score":null,"published":"2026-10-28T10:34:50.674Z","modified":"2026-10-28T10:34:50.674Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://git.kernel.org/stable/c/c1804ef016392dd91267d2207ee43b1de34302ca","https://git.kernel.org/stable/c/a8e45471afa230c1431c26c8e99ec24377e3b514","https://git.kernel.org/stable/c/5271b79b7ad68dcb222e893773f92bdabf7750f3"],"sources":[{"name":"CVE","id":"CVE-2026-99139","modified":"2026-10-28T10:34:50.674Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-99139"}],"assessments":[],"sourceAffected":[],"kev":{"status":"not-listed","checkedAt":"2026-10-28T21:30:35.328Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}