{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-53597","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-10-04T15:40:38.479Z","datePublished":"2025-10-04T15:44:09.616Z","dateUpdated":"2026-08-05T09:15:00.757Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T09:15:00.757Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: fix mid leak during reconnection after timeout threshold\n\nWhen the number of responses with status of STATUS_IO_TIMEOUT\nexceeds a specified threshold (NUM_STATUS_IO_TIMEOUT), we reconnect\nthe connection. But we do not return the mid, or the credits\nreturned for the mid, or reduce the number of in-flight requests.\n\nThis bug could result in the server->in_flight count to go bad,\nand also cause a leak in the mids.\n\nThis change moves the check to a few lines below where the\nresponse is decrypted, even of the response is read from the\ntransform header. This way, the code for returning the mids\ncan be reused.\n\nAlso, the cifs_reconnect was reconnecting just the transport\nconnection before. In case of multi-channel, this may not be\nwhat we want to do after several timeouts. Changed that to\nreconnect the session and the tree too.\n\nAlso renamed NUM_STATUS_IO_TIMEOUT to a more appropriate name\nMAX_STATUS_IO_TIMEOUT."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable code is the CIFS/SMB client demultiplex thread parsing responses received from a remote SMB server over TCP; a malicious, compromised, or MITM-positioned server triggers it purely by the status field it puts in its replies. No local access to the victim is needed.\nAC:L - The server simply returns STATUS_IO_TIMEOUT to six consecutive requests, which deterministically drives the `num_io_timeout > NUM_STATUS_IO_TIMEOUT` path; there is no race, no memory-layout dependency, and no condition outside the attacker's control.\nPR:N - The attacker is the remote peer (or an on-path attacker on an unsigned connection) and holds no privileges whatsoever on the victim client system. Response status codes are attacker-chosen with no authorization gate on the client side.\nUI:N - Exploitation happens on an already-established mount by replying to requests the client issues on its own (writeback, echo, reads), and the client auto-reconnects after each reconnect cycle, so no victim action is required at exploit time.\nS:U - The leaked mids, credits, and stalled I/O are all confined to the kernel of the client host running the cifs module; no security boundary such as a VM or IOMMU domain is crossed.\nC:N - This is a reference/resource leak — an object is over-referenced and never freed. There is no out-of-bounds read, use-after-free, or uninitialized data path, so no information is disclosed to the attacker.\nI:N - No memory is corrupted and no attacker-controlled write occurs; stalled writes leave pages permanently under writeback rather than silently reporting success, so no data is modified or falsified.\nA:H - The bug is repeatable without limit, producing an unbounded kernel memory leak plus permanent `server->in_flight` inflation and credit loss that makes `wait_for_free_credits()` block indefinitely, and skipped read/write callbacks leave pages locked or under writeback forever — yielding unkillable D-state tasks, a hung/unmountable filesystem, and eventual OOM."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/connect.c"],"versions":[{"version":"8e670f77c4a55013db6d23b962f9bf6673a5e7b6","lessThan":"df31d05f0678cdd0796ea19983a2b93edca18bb0","status":"affected","versionType":"git"},{"version":"8e670f77c4a55013db6d23b962f9bf6673a5e7b6","lessThan":"c55901d381a22300c9922170e59704059f50977b","status":"affected","versionType":"git"},{"version":"8e670f77c4a55013db6d23b962f9bf6673a5e7b6","lessThan":"57d25e9905c71133e201f6d06b56a3403d4ad433","status":"affected","versionType":"git"},{"version":"8e670f77c4a55013db6d23b962f9bf6673a5e7b6","lessThan":"69cba9d3c1284e0838ae408830a02c4a063104bc","status":"affected","versionType":"git"},{"version":"fa6d7a5853f93efb088aba36af12cb1944156411","status":"affected","versionType":"git"},{"version":"5.9.5","lessThan":"5.10","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/connect.c"],"versions":[{"version":"5.10","status":"affected"},{"version":"0","lessThan":"5.10","status":"unaffected","versionType":"semver"},{"version":"5.15.150","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.42","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.4.7","lessThanOrEqual":"6.4.*","status":"unaffected","versionType":"semver"},{"version":"6.5","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":"5.10","versionEndExcluding":"5.15.150"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.1.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.4.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9.5"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/df31d05f0678cdd0796ea19983a2b93edca18bb0"},{"url":"https://git.kernel.org/stable/c/c55901d381a22300c9922170e59704059f50977b"},{"url":"https://git.kernel.org/stable/c/57d25e9905c71133e201f6d06b56a3403d4ad433"},{"url":"https://git.kernel.org/stable/c/69cba9d3c1284e0838ae408830a02c4a063104bc"}],"title":"cifs: fix mid leak during reconnection after timeout threshold","x_generator":{"engine":"bippy-1.2.0"}}}}