{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-68082","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-30T09:28:09.367Z","datePublished":"2026-08-08T09:17:45.394Z","dateUpdated":"2026-08-23T12:45:46.891Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-23T12:45:46.891Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: fix two unsafe bare decodes in decode_lockers()\n\ndecode_lockers() in cls_lock_client.c contains two bare decode operations\nthat allow a malicious or compromised OSD to trigger slab-out-of-bounds\nreads:\n\n1. ceph_decode_32(p) at the num_lockers field has no preceding bounds\n   check. ceph_start_decoding() accepts struct_len=0 as valid -- the\n   internal ceph_decode_need(p, end, 0, bad) always passes -- so when an\n   OSD sends struct_len=0, ceph_start_decoding() returns success with\n   p == end. The immediately following bare ceph_decode_32(p) then reads\n   4 bytes past the validated buffer boundary. The garbage value is\n   passed directly to kzalloc_objs() as the locker count.\n\n   The sibling function decode_watchers() in osd_client.c already uses\n   ceph_decode_32_safe() after its own ceph_start_decoding() call.\n   decode_lockers() was the only site using the bare variant.\n\n2. ceph_decode_8(p) after the decode_locker() loop has no preceding\n   bounds check. If an OSD crafts num_lockers such that the loop\n   advances p exactly to end, the subsequent bare ceph_decode_8(p) reads\n   one byte past the validated buffer boundary. The result is passed\n   directly into *type, which is used as a lock type discriminator by\n   callers, giving an OSD-controlled one-byte OOB read with direct\n   influence over the lock type field.\n\nFix both by replacing bare operations with their safe variants:\n  ceph_decode_32(p) -> ceph_decode_32_safe(p, end, *num_lockers,\n                                           err_inval)\n  ceph_decode_8(p)  -> ceph_decode_8_safe(p, end, *type,\n                                          err_free_lockers)\n\nThe goto targets differ intentionally:\n  err_inval: is a new label returning -EINVAL directly. It is used for\n  the pre-allocation failure path where *lockers is not yet allocated\n  and must not be passed to ceph_free_lockers().\n\n  err_free_lockers: is the existing label. It is used for the\n  post-allocation failure path where *lockers is allocated and must\n  be freed.\n\nret is set to -EINVAL before ceph_decode_8_safe() so that\nerr_free_lockers returns the correct error code on bounds violation.\nWithout this, err_free_lockers would return a stale ret value (0 from\nthe successful decode_locker() loop), silently swallowing the error.\n\n-EINVAL is correct for both failure paths. The data received from the\nOSD is structurally malformed. -ENOMEM would misrepresent the failure\nclass to callers and to stable@ backporters triaging error paths.\n\nAttacker model: a malicious or compromised OSD in a multi-tenant Ceph\ndeployment can trigger this against any kernel client that issues the\nlock.get_info class method (e.g. during RBD exclusive lock acquisition).\n\n[ idryomov: trim changelog, formatting ]"}],"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 - The flaw is reached when libceph decodes a crafted MOSDOpReply for the lock.get_info class method received over the Ceph messenger TCP session from a compromised or malicious OSD; no local syscall or ioctl is required on the victim.\nAC:L - A malicious OSD can deterministically send struct_len=0 or craft num_lockers so the decode pointer reaches end, triggering both bare decodes on every attempt without races, special memory layout, or rare kernel configuration.\nPR:N - The attacker acts as the remote Ceph OSD peer and needs no account or privileges on the victim Linux host; any kernel RBD client connected to a multi-tenant or attacker-controlled cluster is exposed during automatic exclusive-lock operations.\nUI:N - Once an RBD image is mapped, ceph_cls_lock_info() is invoked automatically during exclusive-lock acquisition and object-map lock recovery; no further victim user or administrator action is required at exploit time.\nS:U - The slab out-of-bounds reads and any resulting kernel memory corruption occur entirely within the victim host kernel running the Ceph client, without crossing VM, container, or IOMMU security boundaries.\nC:H - Bare ceph_decode_32/8 past the validated reply boundary perform slab out-of-bounds reads of adjacent kernel memory; the leaked u32 can drive kzalloc_objs() sizing and the OOB u8 directly controls the lock-type field consumed by RBD lock logic.\nI:H - Attacker-influenced out-of-bounds values feed heap allocation sizing and lock-type discrimination in kernel lock-handling paths, providing memory-corruption primitives in a privileged parser that can be leveraged beyond simple information disclosure.\nA:H - Slab out-of-bounds reads can trigger KASAN faults or kernel oops on instrumented builds, and attacker-controlled locker counts can force very large kzalloc attempts causing severe memory pressure, OOM conditions, and loss of availability on RBD client hosts."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ceph/cls_lock_client.c"],"versions":[{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"c8ade01170a27d8ede0d761c255268af81e417f8","status":"affected","versionType":"git"},{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"001835c599899ef1bd3506a815110a6374451554","status":"affected","versionType":"git"},{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"7c422364acd93d7da1dfc27d6b54635a269653a1","status":"affected","versionType":"git"},{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"02430f6f729b297e803d0605871f0a670b4eafd6","status":"affected","versionType":"git"},{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"57ba829804fe6d34bbac3b826c4b15c1caa54862","status":"affected","versionType":"git"},{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"89df5d71f83f8e2781286798fd8ae5e42cf5f1a7","status":"affected","versionType":"git"},{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"a54be593d0b749161b08a1e56189b2cb9114267a","status":"affected","versionType":"git"},{"version":"d4ed4a530562881cc5225050e42d96034f405aae","lessThan":"a109a556115271ca7896dcda7b4b7e45e156c227","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ceph/cls_lock_client.c"],"versions":[{"version":"4.9","status":"affected"},{"version":"0","lessThan":"4.9","status":"unaffected","versionType":"semver"},{"version":"5.10.266","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.217","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.184","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.153","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.105","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.46","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.6","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.10.266"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.15.217"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.1.184"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.6.153"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.12.105"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.18.46"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/c8ade01170a27d8ede0d761c255268af81e417f8"},{"url":"https://git.kernel.org/stable/c/001835c599899ef1bd3506a815110a6374451554"},{"url":"https://git.kernel.org/stable/c/7c422364acd93d7da1dfc27d6b54635a269653a1"},{"url":"https://git.kernel.org/stable/c/02430f6f729b297e803d0605871f0a670b4eafd6"},{"url":"https://git.kernel.org/stable/c/57ba829804fe6d34bbac3b826c4b15c1caa54862"},{"url":"https://git.kernel.org/stable/c/89df5d71f83f8e2781286798fd8ae5e42cf5f1a7"},{"url":"https://git.kernel.org/stable/c/a54be593d0b749161b08a1e56189b2cb9114267a"},{"url":"https://git.kernel.org/stable/c/a109a556115271ca7896dcda7b4b7e45e156c227"}],"title":"libceph: fix two unsafe bare decodes in decode_lockers()","x_generator":{"engine":"bippy-1.2.0"}}}}