{"id":"CVE-2026-64535","state":"PUBLISHED","title":"nvmet-tcp: Fix potential UAF when ddgst mismatch","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: Fix potential UAF when ddgst mismatch\n\nShivam Kumar found via vulnerability testing:\nWhen data digest is enabled on an NVMe/TCP connection and a digest\nmismatch occurs on a non-final H2C_DATA PDU during an R2T-based\ndata transfer, the digest error handler in nvmet_tcp_try_recv_ddgst()\ncalls nvmet_req_uninit() — which performs percpu_ref_put() on the\nsubmission queue — but does NOT mark the command as completed. It\ndoes not set cqe->status, does not modify rbytes_done, and does not\nclear any flag. When the subsequent fatal error triggers queue\nteardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands,\nchecks nvmet_tcp_need_data_in() for each one, and finds that the\nalready-uninited command still appears to need data (because\nrbytes_done < transfer_len and cqe->status == 0). It therefore calls\nnvmet_req_uninit() a second time on the same command — a double\npercpu_ref_put against a single percpu_ref_get.","publishedAt":"2026-07-27T06:32:34.859Z","updatedAt":"2026-10-19T20:48:39.004Z","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":"91edfca6f8b364d60cde3ddefaf7d03ddf35774b","status":"affected","lessThan":"dfb902462bca478f050224ec7a7195aafa7643b1","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"7e558308eba14c8136cb1e615f0c850f76d1fc0a","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"96fe2513df590e74b04253a45089cae75569570e","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"e091ff83d962f9ed00d9bd70443676de9fe98bdc","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"6f9442983a3e4227afd1c83a5251ddbca585ea21","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"088ee46c18d99baef453afd74181dd40ade044ad","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"dbbd07d0a7020b80f6a7028e561908f7b83b3d5a","versionType":"git"},{"version":"4b17476d809273617d3317fa0d4ae78aa488d760","status":"affected","versionType":"git"},{"version":"5.10.20","status":"affected","lessThan":"5.10.265","versionType":"semver"},{"version":"5.11.3","status":"affected","lessThan":"5.12","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/nvme/target/tcp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/nvme/target/tcp.c"]}],"references":["https://git.kernel.org/stable/c/dfb902462bca478f050224ec7a7195aafa7643b1","https://git.kernel.org/stable/c/7e558308eba14c8136cb1e615f0c850f76d1fc0a","https://git.kernel.org/stable/c/96fe2513df590e74b04253a45089cae75569570e","https://git.kernel.org/stable/c/e091ff83d962f9ed00d9bd70443676de9fe98bdc","https://git.kernel.org/stable/c/6f9442983a3e4227afd1c83a5251ddbca585ea21","https://git.kernel.org/stable/c/088ee46c18d99baef453afd74181dd40ade044ad","https://git.kernel.org/stable/c/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a"],"weaknesses":["CWE-415"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64535.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64535","state":"PUBLISHED","datePublished":"2026-07-27T06:32:34.859Z","dateUpdated":"2026-10-19T20:48:39.004Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.795Z"},"containers":{"cna":{"title":"nvmet-tcp: Fix potential UAF when ddgst mismatch","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: Fix potential UAF when ddgst mismatch\n\nShivam Kumar found via vulnerability testing:\nWhen data digest is enabled on an NVMe/TCP connection and a digest\nmismatch occurs on a non-final H2C_DATA PDU during an R2T-based\ndata transfer, the digest error handler in nvmet_tcp_try_recv_ddgst()\ncalls nvmet_req_uninit() — which performs percpu_ref_put() on the\nsubmission queue — but does NOT mark the command as completed. It\ndoes not set cqe->status, does not modify rbytes_done, and does not\nclear any flag. When the subsequent fatal error triggers queue\nteardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands,\nchecks nvmet_tcp_need_data_in() for each one, and finds that the\nalready-uninited command still appears to need data (because\nrbytes_done < transfer_len and cqe->status == 0). It therefore calls\nnvmet_req_uninit() a second time on the same command — a double\npercpu_ref_put against a single percpu_ref_get."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"91edfca6f8b364d60cde3ddefaf7d03ddf35774b","status":"affected","lessThan":"dfb902462bca478f050224ec7a7195aafa7643b1","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"7e558308eba14c8136cb1e615f0c850f76d1fc0a","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"96fe2513df590e74b04253a45089cae75569570e","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"e091ff83d962f9ed00d9bd70443676de9fe98bdc","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"6f9442983a3e4227afd1c83a5251ddbca585ea21","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"088ee46c18d99baef453afd74181dd40ade044ad","versionType":"git"},{"version":"fda871c0ba5d2eed2cd1c881573168129da70058","status":"affected","lessThan":"dbbd07d0a7020b80f6a7028e561908f7b83b3d5a","versionType":"git"},{"version":"4b17476d809273617d3317fa0d4ae78aa488d760","status":"affected","versionType":"git"},{"version":"5.10.20","status":"affected","lessThan":"5.10.265","versionType":"semver"},{"version":"5.11.3","status":"affected","lessThan":"5.12","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/nvme/target/tcp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/nvme/target/tcp.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/dfb902462bca478f050224ec7a7195aafa7643b1"},{"url":"https://git.kernel.org/stable/c/7e558308eba14c8136cb1e615f0c850f76d1fc0a"},{"url":"https://git.kernel.org/stable/c/96fe2513df590e74b04253a45089cae75569570e"},{"url":"https://git.kernel.org/stable/c/e091ff83d962f9ed00d9bd70443676de9fe98bdc"},{"url":"https://git.kernel.org/stable/c/6f9442983a3e4227afd1c83a5251ddbca585ea21"},{"url":"https://git.kernel.org/stable/c/088ee46c18d99baef453afd74181dd40ade044ad"},{"url":"https://git.kernel.org/stable/c/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a"}],"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 vulnerable NVMe/TCP target receive worker processes attacker-controlled H2C_DATA PDUs received through a listening TCP socket, making it remotely network reachable.\nAC:L - The attacker controls digest negotiation, PDU chunking, transfer length, and digest contents, allowing a non-final digest mismatch to be triggered deterministically while keeping other I/O outstanding.\nPR:N - A reasonable non-TLS target deployment using allow_any_host requires no credentials or local capabilities; the remote peer can negotiate data digests and submit the malicious protocol sequence directly.\nUI:N - Exploitation requires only network protocol traffic and no action by a victim user.\nS:U - The vulnerable receive processing and resulting kernel compromise occur within the target host's existing kernel security authority.\nC:H - The premature reference release can free queue, request, response-buffer, and percpu-ref state while asynchronous completions still access it, creating a kernel UAF capable of arbitrary memory disclosure.\nI:H - The kernel UAF exposes writes through reclaimed request and queue structures and is plausibly exploitable for arbitrary kernel memory modification or code execution.\nA:H - The refcount corruption can cause a permanent workqueue teardown deadlock, while the resulting UAF can also produce an oops or kernel panic; the network trigger can be repeated."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-19T16:28:23.449Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.20","versionEndExcluding":"5.10.265"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64535","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:41:56.047833Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-415","lang":"en","type":"CWE","description":"CWE-415 Double Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:48:39.004Z"}}]}}}