{"id":"CVE-2023-53751","state":"PUBLISHED","title":"cifs: fix potential use-after-free bugs in TCP_Server_Info::hostname","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: fix potential use-after-free bugs in TCP_Server_Info::hostname\n\nTCP_Server_Info::hostname may be updated once or many times during\nreconnect, so protect its access outside reconnect path as well and\nthen prevent any potential use-after-free bugs.","publishedAt":"2025-12-08T01:19:11.160Z","updatedAt":"2026-08-05T09:15:47.928Z","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":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"64d62ac6d6514cba1305bd08e271ec1843bdd612","versionType":"git"},{"version":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"c511954bf142fe1995aec3c739a9f1a76990283a","versionType":"git"},{"version":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"0b08c4c499200be67d54c439d56e5ea866869945","versionType":"git"},{"version":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"90c49fce1c43e1cc152695e20363ff5087897c09","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/cifs/cifs_debug.c","fs/cifs/cifs_debug.h","fs/cifs/connect.c","fs/cifs/sess.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.0","versionType":"semver"},{"version":"6.1.28","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.2.15","status":"unaffected","lessThanOrEqual":"6.2.*","versionType":"semver"},{"version":"6.3.2","status":"unaffected","lessThanOrEqual":"6.3.*","versionType":"semver"},{"version":"6.4","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/cifs/cifs_debug.c","fs/cifs/cifs_debug.h","fs/cifs/connect.c","fs/cifs/sess.c"]}],"references":["https://git.kernel.org/stable/c/64d62ac6d6514cba1305bd08e271ec1843bdd612","https://git.kernel.org/stable/c/c511954bf142fe1995aec3c739a9f1a76990283a","https://git.kernel.org/stable/c/0b08c4c499200be67d54c439d56e5ea866869945","https://git.kernel.org/stable/c/90c49fce1c43e1cc152695e20363ff5087897c09"],"weaknesses":[],"ingestedAt":"2026-10-29T20:06:33.064Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2023/53xxx/CVE-2023-53751.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-53751","state":"PUBLISHED","datePublished":"2025-12-08T01:19:11.160Z","dateUpdated":"2026-08-05T09:15:47.928Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-12-08T01:18:04.279Z"},"containers":{"cna":{"title":"cifs: fix potential use-after-free bugs in TCP_Server_Info::hostname","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: fix potential use-after-free bugs in TCP_Server_Info::hostname\n\nTCP_Server_Info::hostname may be updated once or many times during\nreconnect, so protect its access outside reconnect path as well and\nthen prevent any potential use-after-free bugs."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"64d62ac6d6514cba1305bd08e271ec1843bdd612","versionType":"git"},{"version":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"c511954bf142fe1995aec3c739a9f1a76990283a","versionType":"git"},{"version":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"0b08c4c499200be67d54c439d56e5ea866869945","versionType":"git"},{"version":"93d5cb517db39e8af8d1292f9e785e4983b7f708","status":"affected","lessThan":"90c49fce1c43e1cc152695e20363ff5087897c09","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/cifs/cifs_debug.c","fs/cifs/cifs_debug.h","fs/cifs/connect.c","fs/cifs/sess.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.0","versionType":"semver"},{"version":"6.1.28","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.2.15","status":"unaffected","lessThanOrEqual":"6.2.*","versionType":"semver"},{"version":"6.3.2","status":"unaffected","lessThanOrEqual":"6.3.*","versionType":"semver"},{"version":"6.4","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/cifs/cifs_debug.c","fs/cifs/cifs_debug.h","fs/cifs/connect.c","fs/cifs/sess.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/64d62ac6d6514cba1305bd08e271ec1843bdd612"},{"url":"https://git.kernel.org/stable/c/c511954bf142fe1995aec3c739a9f1a76990283a"},{"url":"https://git.kernel.org/stable/c/0b08c4c499200be67d54c439d56e5ea866869945"},{"url":"https://git.kernel.org/stable/c/90c49fce1c43e1cc152695e20363ff5087897c09"}],"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 vulnerability is in the CIFS/SMB client's handling of remote server data — the freed/reallocated `hostname` is derived from server-supplied DFS referral targets, and both the free side (forced reconnects) and the read side (error-path `cifs_server_dbg(VFS,...)` on malformed or bad-signature responses) are driven entirely by a remote SMB peer or an on-path network attacker.\nAC:L - The attacker controls both sides of the race: it can force unlimited reconnect cycles by dropping the TCP connection, chooses DFS target names so it controls the size and content of the freed/reallocated string for heap grooming, and can trigger the unlocked readers on demand via malformed responses, with unlimited retries.\nPR:N - No credentials or privileges on the target are required — the attacker is the remote SMB server or a network attacker, and the reader side is additionally reachable by any unprivileged local user through the world-readable (0444) /proc/fs/cifs/DebugData and 0644 /proc/fs/cifs/Stats.\nUI:N - Against a host with an already-established DFS CIFS mount (routine on enterprise servers and appliances), the attacker triggers reconnects and error paths on its own; no action by any user is needed at attack time.\nS:U - The use-after-free is in kernel memory and its impact stays within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - `seq_printf(\"%s\", server->hostname)` on the dangling pointer copies freed heap memory into the world-readable /proc/fs/cifs/DebugData output, reading until an arbitrary NUL byte, giving an unbounded kernel heap disclosure whose contents the attacker can groom; the same data also leaks to dmesg via `cifs_server_dbg`.\nI:H - This is a use-after-free on an attacker-size-controlled slab object with a racing free/reassign of the same pointer, which enables heap spraying and reclaim of the freed slot; per kernel UAF scoring this is treated as exploitable for control-flow/memory corruption.\nA:H - Dereferencing the freed string over poisoned, unmapped, or reallocated memory produces a kernel oops/panic, and the attacker can repeat the reconnect-driven race indefinitely."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T09:15:47.928Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.0","versionEndExcluding":"6.1.28"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.0","versionEndExcluding":"6.2.15"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.0","versionEndExcluding":"6.3.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.0","versionEndExcluding":"6.4"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}