{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-37776","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T04:51:23.939Z","datePublished":"2025-05-01T13:07:14.998Z","dateUpdated":"2026-08-05T11:57:27.462Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:57:27.462Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free in smb_break_all_levII_oplock()\n\nThere is a room in smb_break_all_levII_oplock that can cause racy issues\nwhen unlocking in the middle of the loop. This patch use read lock\nto protect whole loop."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - ksmbd is the in-kernel SMB server on TCP/445, and every trigger path (SMB2 WRITE, CREATE with O_TRUNC, SET_INFO alloc-size/rename, IOCTL copychunk/zero-data, LOCK) is driven entirely by remote SMB2 traffic. No local access is required.\nAC:L - The attacker controls both sides of the race: one connection holds the level-II oplock and simply withholds the SMB2_OPLOCK_BREAK ack, pinning the RCU-unlocked window open for up to OPLOCK_WAIT_TIME (35 s), while other connections close handles on the same inode to drive opinfo_del()/opinfo_put(). An attacker-created race with a multi-second window is reliably winnable and repeatable.\nPR:L - All call sites dereference work->tcon->share_conf, so a completed SESSION_SETUP and TREE_CONNECT are needed — any unprivileged share account (including guest where \"map to guest\" is configured) suffices, with no administrative rights. This matches the sibling post-authentication ksmbd UAFs.\nUI:N - The attacker drives every step from its own SMB connections — taking the oplock, stalling the break ack, and closing handles concurrently. No action by an administrator or any other client is needed.\nS:U - The freed object and the resulting corruption are both inside the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The ~176-byte oplock_info lives in the general kmalloc-192 cache and is remotely sprayable, so the freed object can be reclaimed with attacker-controlled bytes at the op_entry.next offset, yielding a chosen brk_op whose ->conn and ->o_lease->state dereferences give arbitrary kernel memory disclosure.\nI:H - With a controlled brk_op pointer, atomic_inc_not_zero(&brk_op->refcount) is an arbitrary-address increment write, and oplock_break() then manipulates wait-queue lists and queues work off the fake object — a use-after-free that is exploitable for control-flow hijack and arbitrary kernel code execution.\nA:H - Even unweaponized, following op_entry.next out of a freed oplock_info dereferences freed/poisoned memory and reliably oopses or panics the kernel, and the attacker can repeat the sequence to keep the SMB server down."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/oplock.c","fs/smb/server/oplock.h"],"versions":[{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"296cb5457cc6f4a754c4ae29855f8a253d52bcc6","status":"affected","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"d54ab1520d43e95f9b2e22d7a05fc9614192e5a5","status":"affected","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"d73686367ad68534257cd88a36ca3c52cb8b81d8","status":"affected","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"18b4fac5ef17f77fed9417d22210ceafd6525fc7","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/oplock.c","fs/smb/server/oplock.h"],"versions":[{"version":"5.15","status":"affected"},{"version":"0","lessThan":"5.15","status":"unaffected","versionType":"semver"},{"version":"6.6.88","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.25","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.14.4","lessThanOrEqual":"6.14.*","status":"unaffected","versionType":"semver"},{"version":"6.15","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":"5.15","versionEndExcluding":"6.6.88"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.12.25"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.14.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.15"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/296cb5457cc6f4a754c4ae29855f8a253d52bcc6"},{"url":"https://git.kernel.org/stable/c/d54ab1520d43e95f9b2e22d7a05fc9614192e5a5"},{"url":"https://git.kernel.org/stable/c/d73686367ad68534257cd88a36ca3c52cb8b81d8"},{"url":"https://git.kernel.org/stable/c/18b4fac5ef17f77fed9417d22210ceafd6525fc7"}],"title":"ksmbd: fix use-after-free in smb_break_all_levII_oplock()","x_generator":{"engine":"bippy-1.2.0"}}}}