{"id":"DEBIAN-CVE-2026-63801","details":"In the Linux kernel, the following vulnerability has been resolved:  tipc: fix slab-use-after-free Read in tipc_aead_decrypt_done  tipc_aead_decrypt() goes straight from tipc_bearer_hold(b) to crypto_aead_decrypt(req) without taking a reference on the netns, unlike the encrypt path. When crypto_aead_decrypt() is offloaded asynchronously (e.g. the SIMD aead wrapper queuing to cryptd), the cryptd worker runs tipc_aead_decrypt_done() later. If the bearer's netns is torn down in the meantime, cleanup_net() -\u003e tipc_exit_net() -\u003e tipc_crypto_stop() frees the per-netns tipc_crypto, and the completion then reads it: tipc_aead_decrypt_done() dereferences aead-\u003ecrypto-\u003estats and aead-\u003ecrypto-\u003enet, and tipc_crypto_rcv_complete() dereferences aead-\u003ecrypto-\u003eaead[] and the node table -- reading freed memory.  Decoded KASAN splat (v7.1-rc7, CONFIG_KASAN_INLINE + TIPC + TIPC_CRYPTO):    BUG: KASAN: slab-use-after-free in tipc_aead_decrypt_done (net/tipc/crypto.c:999)   Read of size 8 at addr ffff8881056258a8 by task kworker/u16:2/51   Workqueue: events_unbound   Call Trace:    tipc_aead_decrypt_done (net/tipc/crypto.c:999)    process_one_work (kernel/workqueue.c:3314)    worker_thread (kernel/workqueue.c:3397 kernel/workqueue.c:3478)    kthread (kernel/kthread.c:436)    ret_from_fork (arch/x86/kernel/process.c:158)    ret_from_fork_asm (arch/x86/entry/entry_64.S:245)    Allocated by task 169:    __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415)    tipc_crypto_start (net/tipc/crypto.c:1502)    tipc_init_net (net/tipc/core.c:72)    ops_init (net/core/net_namespace.c:137)    setup_net (net/core/net_namespace.c:446)    copy_net_ns (net/core/net_namespace.c:579)    create_new_namespaces (kernel/nsproxy.c:132)    __x64_sys_unshare (kernel/fork.c:3316)    do_syscall_64 (arch/x86/entry/syscall_64.c:63)    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)    Freed by task 8:    kfree (mm/slub.c:6566)    tipc_exit_net (net/tipc/core.c:119)    cleanup_net (net/core/net_namespace.c:704)    process_one_work (kernel/workqueue.c:3314)    kthread (kernel/kthread.c:436)  This is the same class of bug that commit e279024617134 (\"net/tipc: fix slab-use-after-free Read in tipc_aead_encrypt_done\") fixed for the encrypt side. The encrypt path takes maybe_get_net(aead-\u003ecrypto-\u003enet) before crypto_aead_encrypt() and drops it with put_net() on the synchronous return paths and in tipc_aead_encrypt_done(); the -EINPROGRESS/-EBUSY return keeps the reference for the async callback to release. The decrypt path was left without the equivalent guard.  Mirror the encrypt-side fix on the decrypt path: take a net reference before crypto_aead_decrypt() (failing with -ENODEV and the matching bearer put if it cannot be acquired), keep it across the -EINPROGRESS/-EBUSY async return, and drop it with put_net() on the synchronous success/error return and at the end of tipc_aead_decrypt_done().  Reproduced under KASAN on v7.1-rc7: a UDP bearer with a cluster key is flooded with crafted encrypted frames from an unknown peer (driving the cluster-key decrypt path) while the bearer's netns is repeatedly torn down. The completion must run asynchronously to outlive tipc_crypto_stop(); on x86 the stock aesni gcm(aes) now decrypts synchronously, so the async path was exercised via cryptd offload. The unguarded aead-\u003ecrypto dereference in tipc_aead_decrypt_done() is the unpatched upstream path; tipc_aead_decrypt() still lacks maybe_get_net(aead-\u003ecrypto-\u003enet), so the completion can outlive the free on any config where crypto_aead_decrypt() goes async.  Found by 0sec automated security-research tooling (https://0sec.ai).","modified":"2026-09-01T16:06:54.228242951Z","published":"2026-07-19T12:16:52.680Z","upstream":["CVE-2026-63801"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-63801"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.177-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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