{"id":"CVE-2026-80521","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-80521","summary":"af_unix: Unlink scc_entry in unix_del_edge().","details":"In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Unlink scc_entry in unix_del_edge().\n\nKyle Zeng reported that GC could free a dead SCC partially.\n\nThe scenario is as follows:\n\n   1) Create two SCCs:\n\n       X -.   A <-> B\n       ^--'\n\n   2) Run the following concurrently:\n\n      2-1) send() sk-B to sk-B from sk-X\n      2-2) close() both A and B\n\nAt 2-1), there is a small window where unix_add_edges()\npublishes a new edge (B <-> B) to GC but its skb is not queued\nby skb_queue_tail().\n\nIf 2-2) completes before skb_queue_tail() and GC is triggered,\nit judges A <-> B as dead, but B is not freed because GC cannot\ncollect the not-yet-queued skb holding the B <-> B edge.\n\n       X -.   A <-> B -. This edge is visible\n       ^--'         ^..'  but skb is not\n\nThis itself is not a problem since the next GC run will judge\nB as dead as well and free it finally.\n\n       X -.   A <.> B -.\n       ^--'         ^--'\n\nHowever, X's SCC forces the next GC to call unix_walk_scc_fast(),\nand it iterates over A through B's scc_entry.\n\nLet's unlink scc_entry before freeing the vertex in unix_del_edge().","published":"2026-08-26T14:37:02.589Z","modified":"2026-08-28T03:47:27.319815339Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"7.1.10"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/594d905195024b228c962627ae5ae7c17bd582a4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e3702470ced94fad74d71e2232f022d2eb752a6d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80521.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80521"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-28T03:47:27.319815339Z"}}