{"id":"CVE-2026-80521","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-80521","generatedAt":"2026-10-28T02:17:38.719Z","title":"In the Linux kernel, the following vulnerability has been resolved: af_unix: Unlink scc_entry in unix_del_edge().","description":"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":"2026-08-26T15:17:06.000Z","lastModified":"2026-10-03T11:17:39.000Z","status":"Received","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","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"},"cwe":[],"affected":[],"epss":{"score":0.00178,"percentile":0.07262,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.18%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/1293fd69a50d188a5788b08ba3741a3e86be1608","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2b6c2842692d08e7acaf32d1eb47f95def35f3fe","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/594d905195024b228c962627ae5ae7c17bd582a4","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6fda5c51b8e43a8440f76e65c89d9f95ddb2ef33","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e3702470ced94fad74d71e2232f022d2eb752a6d","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fe198b077864feafd4aa4b33b1a5ce26f50195a2","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80521","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}