{"cve":"CVE-2026-63801","nvd":{"published":"2026-07-19T12:16:52.680","modified":"2026-10-19T20:19:20.493","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix slab-use-after-free Read in tipc_aead_decrypt_done\n\ntipc_aead_decrypt() goes straight from tipc_bearer_hold(b) to\ncrypto_aead_decrypt(req) without taking a reference on the netns, unlike\nthe encrypt path. When crypto_aead_decrypt() is offloaded asynchronously\n(e.g. the SIMD aead wrapper queuing to cryptd), the cryptd worker runs\ntipc_aead_decrypt_done() later. If the bearer's netns is torn down in the\nmeantime, cleanup_net() -> tipc_exit_net() -> tipc_crypto_stop() frees the\nper-netns tipc_crypto, and the completion then reads it:\ntipc_aead_decrypt_done() dereferences aead->crypto->stats and\naead->crypto->net, and tipc_crypto_rcv_complete() dereferences\naead->crypto->aead[] and the node table -- reading freed memory.\n\nDecoded KASAN splat (v7.1-rc7, CONFIG_KASAN_INLINE + TIPC + TIPC_CRYPTO):\n\n  BUG: KASAN: slab-use-after-free in tipc_aead_decrypt_done (net/tipc/crypto.c:999)\n  Read of size 8 at addr ffff8881056258a8 by task kworker/u16:2/51\n  Workqueue: events_unbound\n  Call Trace:\n   tipc_aead_decrypt_done (net/tipc/crypto.c:999)\n   process_one_work (kernel/workqueue.c:3314)\n   worker_thread (kernel/workqueue.c:3397 kernel/workqueue.c:3478)\n   kthread (kernel/kthread.c:436)\n   ret_from_fork (arch/x86/kernel/process.c:158)\n   ret_from_fork_asm (arch/x86/entry/entry_64.S:245)\n\n  Allocated by task 169:\n   __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415)\n   tipc_crypto_start (net/tipc/crypto.c:1502)\n   tipc_init_net (net/tipc/core.c:72)\n   ops_init (net/core/net_namespace.c:137)\n   setup_net (net/core/net_namespace.c:446)\n   copy_net_ns (net/core/net_namespace.c:579)\n   create_new_namespaces (kernel/nsproxy.c:132)\n   __x64_sys_unshare (kernel/fork.c:3316)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:63)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n\n  Freed by task 8:\n   kfree (mm/slub.c:6566)\n   tipc_exit_net (net/tipc/core.c:119)\n   cleanup_net (net/core/net_namespace.c:704)\n   process_one_work (kernel/workqueue.c:3314)\n   kthread (kernel/kthread.c:436)\n\nThis is the same class of bug that commit e279024617134 (\"net/tipc: fix\nslab-use-after-free Read in tipc_aead_encrypt_done\") fixed for the encrypt\nside. The encrypt path takes maybe_get_net(aead->crypto->net) before\ncrypto_aead_encrypt() and drops it with put_net() on the synchronous\nreturn paths and in tipc_aead_encrypt_done(); the -EINPROGRESS/-EBUSY\nreturn keeps the reference for the async callback to release. The decrypt\npath was left without the equivalent guard.\n\nMirror the encrypt-side fix on the decrypt path: take a net reference\nbefore crypto_aead_decrypt() (failing with -ENODEV and the matching\nbearer put if it cannot be acquired), keep it across the\n-EINPROGRESS/-EBUSY async return, and drop it with put_net() on the\nsynchronous success/error return and at the end of\ntipc_aead_decrypt_done().\n\nReproduced under KASAN on v7.1-rc7: a UDP bearer with a cluster key is\nflooded with crafted encrypted frames from an unknown peer (driving the\ncluster-key decrypt path) while the bearer's netns is repeatedly torn\ndown. The completion must run asynchronously to outlive\ntipc_crypto_stop(); on x86 the stock aesni gcm(aes) now decrypts\nsynchronously, so the async path was exercised via cryptd offload. The\nunguarded aead->crypto dereference in tipc_aead_decrypt_done() is the\nunpatched upstream path; tipc_aead_decrypt() still lacks\nmaybe_get_net(aead->crypto->net), so the completion can outlive the free\non any config where crypto_aead_decrypt() goes async.\n\nFound by 0sec automated security-research tooling (https://0sec.ai).","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/0a780653b2a7569a7af9be7d0b00b1251baca63a","https://git.kernel.org/stable/c/171d31245d11bf84836fad3b394cb465a4d008ec","https://git.kernel.org/stable/c/1eea5e1820a2f5164d706bd1277bc97ff31ce32d","https://git.kernel.org/stable/c/2d1f21419ec121232c916d3a3fc9b6766473a0e7","https://git.kernel.org/stable/c/bda3348872a2ef0d19f2df6aa8cb5025adce2f20"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2026-63801","score":0.00513,"percentile":0.43452,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}