{"id":"CVE-2026-64439","state":"PUBLISHED","title":"crypto: krb5 - filter out async aead implementations at alloc","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: krb5 - filter out async aead implementations at alloc\n\nkrb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and\nrfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL\ncompletion callback and treat any negative return from\ncrypto_aead_{encrypt,decrypt}() as terminal, falling through to\nkfree_sensitive(buffer).  When the encrypt_name resolves to an\nasync AEAD instance the request returns -EINPROGRESS, the buffer\nis freed while the backend's worker still holds a pointer, and the\nworker dereferences the freed slab on completion.\n\nKASAN report under UML+SLUB with a synthetic async aead backend\nbound to krb5->encrypt_name:\n\n  BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7\n\nThe helpers were written synchronously, so filter the async\ninstances out at allocation time instead of plumbing\ncrypto_wait_req() through every call site.\n\nReachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and\nnet/ceph/crypto.c on systems with an async AEAD provider bound to\nthe krb5 enctype name.","publishedAt":"2026-07-25T08:51:12.422Z","updatedAt":"2026-08-17T04:55:40.947Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"00244da40f7821b242c4612428d4192230dba27f","status":"affected","lessThan":"ef6feb77e2d91761427c5b773edc9c97e1b706ad","versionType":"git"},{"version":"00244da40f7821b242c4612428d4192230dba27f","status":"affected","lessThan":"2b7bd6dccff14b8b632c5244f1fd506918077221","versionType":"git"},{"version":"00244da40f7821b242c4612428d4192230dba27f","status":"affected","lessThan":"6c9dddeb582fde005360f4fe02c760d45ca05fb5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5/krb5_api.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5/krb5_api.c"]}],"references":["https://git.kernel.org/stable/c/ef6feb77e2d91761427c5b773edc9c97e1b706ad","https://git.kernel.org/stable/c/2b7bd6dccff14b8b632c5244f1fd506918077221","https://git.kernel.org/stable/c/6c9dddeb582fde005360f4fe02c760d45ca05fb5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64439.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64439","state":"PUBLISHED","datePublished":"2026-07-25T08:51:12.422Z","dateUpdated":"2026-08-17T04:55:40.947Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.788Z"},"containers":{"cna":{"title":"crypto: krb5 - filter out async aead implementations at alloc","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: krb5 - filter out async aead implementations at alloc\n\nkrb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and\nrfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL\ncompletion callback and treat any negative return from\ncrypto_aead_{encrypt,decrypt}() as terminal, falling through to\nkfree_sensitive(buffer).  When the encrypt_name resolves to an\nasync AEAD instance the request returns -EINPROGRESS, the buffer\nis freed while the backend's worker still holds a pointer, and the\nworker dereferences the freed slab on completion.\n\nKASAN report under UML+SLUB with a synthetic async aead backend\nbound to krb5->encrypt_name:\n\n  BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7\n\nThe helpers were written synchronously, so filter the async\ninstances out at allocation time instead of plumbing\ncrypto_wait_req() through every call site.\n\nReachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and\nnet/ceph/crypto.c on systems with an async AEAD provider bound to\nthe krb5 enctype name."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"00244da40f7821b242c4612428d4192230dba27f","status":"affected","lessThan":"ef6feb77e2d91761427c5b773edc9c97e1b706ad","versionType":"git"},{"version":"00244da40f7821b242c4612428d4192230dba27f","status":"affected","lessThan":"2b7bd6dccff14b8b632c5244f1fd506918077221","versionType":"git"},{"version":"00244da40f7821b242c4612428d4192230dba27f","status":"affected","lessThan":"6c9dddeb582fde005360f4fe02c760d45ca05fb5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5/krb5_api.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5/krb5_api.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/ef6feb77e2d91761427c5b773edc9c97e1b706ad"},{"url":"https://git.kernel.org/stable/c/2b7bd6dccff14b8b632c5244f1fd506918077221"},{"url":"https://git.kernel.org/stable/c/6c9dddeb582fde005360f4fe02c760d45ca05fb5"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - An unauthenticated remote peer can reach the vulnerable Kerberos decrypt helper through the UDP RxRPC/RxGK RESPONSE path; Ceph and AFS also expose network-driven paths.\nAC:L - Once an async AEAD implementation is selected, each accepted operation can return -EINPROGRESS and trigger the UAF. The attacker controls and can repeatedly invoke the packet flow, enabling heap grooming and race amplification.\nPR:N - RxGK decrypts the attacker-supplied token before validating the ticket, nonce, or authenticator. Looking up an installed server key selects the cipher but does not authenticate the peer.\nUI:N - A listening service processes the challenge and malicious response automatically without any victim action.\nS:U - Exploitation compromises resources governed by the same host kernel security authority and does not inherently cross a VM, IOMMU, or equivalent boundary.\nC:H - The freed request contains transform, callback, context, IV, and scatterlist-related state that can be reclaimed or accessed asynchronously, supporting controlled kernel-memory disclosure.\nI:H - The backend can write through stale scatterlist pointers, while reclaimed callback and request fields can enable arbitrary memory corruption or control-flow hijacking.\nA:H - The async worker dereferences freed or zeroed request state, allowing a repeatable kernel oops or panic; the defect has also been directly observed as a KASAN slab use-after-free."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:55:40.947Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}