{"id":"CVE-2026-31536","state":"PUBLISHED","title":"smb: server: let send_done handle a completion without IB_SEND_SIGNALED","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: server: let send_done handle a completion without IB_SEND_SIGNALED\n\nWith smbdirect_send_batch processing we likely have requests without\nIB_SEND_SIGNALED, which will be destroyed in the final request\nthat has IB_SEND_SIGNALED set.\n\nIf the connection is broken all requests are signaled\neven without explicit IB_SEND_SIGNALED.","publishedAt":"2026-04-24T14:30:24.224Z","updatedAt":"2026-08-05T12:23:21.869Z","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":"0626e6641f6b467447c81dd7678a69c66f7746cf","status":"affected","lessThan":"24082642654f3e5149913946e89c00a297a8868f","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","status":"affected","lessThan":"e38b415c024bc3b6321bf8650dbf3f4aab8e74b3","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","status":"affected","lessThan":"9da82dc73cb03e85d716a2609364572367a5ff47","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/transport_rdma.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"6.18.11","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.1","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/transport_rdma.c"]}],"references":["https://git.kernel.org/stable/c/24082642654f3e5149913946e89c00a297a8868f","https://git.kernel.org/stable/c/e38b415c024bc3b6321bf8650dbf3f4aab8e74b3","https://git.kernel.org/stable/c/9da82dc73cb03e85d716a2609364572367a5ff47"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31536.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31536","state":"PUBLISHED","datePublished":"2026-04-24T14:30:24.224Z","dateUpdated":"2026-08-05T12:23:21.869Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.113Z"},"containers":{"cna":{"title":"smb: server: let send_done handle a completion without IB_SEND_SIGNALED","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: server: let send_done handle a completion without IB_SEND_SIGNALED\n\nWith smbdirect_send_batch processing we likely have requests without\nIB_SEND_SIGNALED, which will be destroyed in the final request\nthat has IB_SEND_SIGNALED set.\n\nIf the connection is broken all requests are signaled\neven without explicit IB_SEND_SIGNALED."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","status":"affected","lessThan":"24082642654f3e5149913946e89c00a297a8868f","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","status":"affected","lessThan":"e38b415c024bc3b6321bf8650dbf3f4aab8e74b3","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","status":"affected","lessThan":"9da82dc73cb03e85d716a2609364572367a5ff47","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/transport_rdma.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"6.18.11","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.1","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/transport_rdma.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/24082642654f3e5149913946e89c00a297a8868f"},{"url":"https://git.kernel.org/stable/c/e38b415c024bc3b6321bf8650dbf3f4aab8e74b3"},{"url":"https://git.kernel.org/stable/c/9da82dc73cb03e85d716a2609364572367a5ff47"}],"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 code is in ksmbd SMB Direct, which accepts remote RDMA/SMB Direct connections on network ports 445 and 5445 and processes peer-controlled SMB Direct traffic.\nAC:L - An attacker can negotiate a small SMB Direct max receive size to force batched multi-WR sends, then break the connection to make unsignaled sends complete with error. The disconnect/error condition is attacker-controlled rather than an external race.\nPR:N - The path is reachable before SMB authentication: SMB Direct negotiation completes first, and SMB2 NEGOTIATE/SESSION_SETUP do not require a valid session. A pre-auth remote client can trigger outbound responses through the vulnerable RDMA send batching path.\nUI:N - No victim user action is required once ksmbd with SMB Direct is listening; the attacker only needs to connect and send protocol messages.\nS:U - The impact is within the kernel/ksmbd host security authority and does not cross a hypervisor, IOMMU, or separate sandbox boundary.\nC:H - The bug is a use-after-free/double-free style memory corruption in RDMA send objects, and kernel UAFs can be shaped into disclosure primitives through heap reuse.\nI:H - The freed `smbdirect_send_io` objects contain list pointers, CQ callbacks, and work request state; corrupting or reusing them can plausibly support arbitrary write or control-flow hijack.\nA:H - Even without full exploitation, the UAF/list corruption is expected to cause kernel warnings, crashes, or hangs during RDMA QP drain and completion handling."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:23:21.869Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.18.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.19.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}