CVE-2026-89546

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89546", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.722Z", "datePublished": "2026-09-11T19:44:21.898Z", "dateUpdated": "2026-10-19T08:48:37.920Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:37.920Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: close backchannel before destroying callback service\n\nA backchannel receive can complete a request while the NFS callback\nservice is being torn down. xprt_complete_bc_request() removes the\nrequest from bc_pa_list, drops bc_alloc_count, marks the request in use,\nand then asks xprt_enqueue_bc_request() to hand it to the callback\nservice.\n\nIf teardown has already cleared xprt->bc_serv, xprt_enqueue_bc_request()\ncurrently returns without enqueueing or freeing the committed request.\nThe xprt_get() taken on entry is leaked as well. If the producer wins\nthe race before bc_serv is cleared, it can also enqueue onto sv_cb_list\nafter nfs_callback_down() has stopped the callback threads, leaving the\nrequest linked to a svc_serv that is about to be freed.\n\nClose the producer side before callback threads are stopped. Add\nxprt_svc_shutdown_bc() to clear xprt->bc_serv under bc_pa_lock, and call\nit on callback shutdown and callback-start failure before stopping the\nservice threads. Requests that lose the NULL transition in\nxprt_enqueue_bc_request() are released through the normal backchannel\nfree path after balancing bc_slot_count. Finally, drain any remaining\nsv_cb_list requests after the callback threads have stopped and before\nsvc_destroy() frees the service."}], "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 producer is xs_read_stream_call()/rpcrdma_bc_receive_call() handling RPC_CALL messages on the established NFSv4.1+ client TCP or RPC/RDMA transport; a malicious NFS server sends backchannel frames on that connection and reaches the bug without local access.\nAC:L - The attacker controls both sides of the race: they emit backchannel RPC_CALLs on the still-live xprt and force callback teardown via failed session setup, autofs expiry, or unmount, leaving rpc_rqst objects on sv_cb_list when svc_destroy() frees svc_serv.\nPR:N - A remote NFS peer needs no account or capability on the victim; backchannel RPC_CALLs are accepted on the connected NFSv4.1+ transport once a mount or mount attempt exists, with no local privileges at exploit time.\nUI:N - Boot-time, autofs, and Kubernetes NFSv4.1+ mounts are common; after that session exists the attacker drives backchannel traffic and callback teardown without further interactive victim action such as a manual mount.\nS:U - The use-after-free corrupts the in-kernel nfs_callback svc_serv and rpc_rqst objects on the client host and does not cross a VM, IOMMU, or other security-authority boundary.\nC:H - A raced enqueue leaves an in-use rpc_rqst linked into a freed svc_serv (sv_cb_list/sv_pools), and unlocked bc_serv readers can follow that dangling pointer, yielding a kernel-heap use-after-free read primitive.\nI:H - Use-after-free of svc_serv with queued rpc_rqst and svc_pool_wake_idle_thread on dying callback pools enables heap reuse of RPC service control structures, a standard kernel write and control-flow hijack primitive.\nA:H - svc_destroy() of a callback service that still has live backchannel requests, plus dereference of xprt->bc_serv after free, causes kernel oops or panic; the leak path also orphans rpc_rqst objects and xprt references."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/nfs/callback.c", "include/linux/sunrpc/bc_xprt.h", "net/sunrpc/backchannel_rqst.c"], "versions": [{"version": "441244d4273a8037b265fd254dfdaca5fa736ee2", "lessThan": "6debde9e3e6ae21dcca75837b4247b13ca4ea2b8", "status": "affected", "versionType": "git"}, {"version": "441244d4273a8037b265fd254dfdaca5fa736ee2", "lessThan": "3674f780f47d2906b5a0f7199b66973067bdfeca", "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/nfs/callback.c", "include/linux/sunrpc/bc_xprt.h", "net/sunrpc/backchannel_rqst.c"], "versions": [{"version": "6.19", "status": "affected"}, {"version": "0", "lessThan": "6.19", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "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": "6.19", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/6debde9e3e6ae21dcca75837b4247b13ca4ea2b8"}, {"url": "https://git.kernel.org/stable/c/3674f780f47d2906b5a0f7199b66973067bdfeca"}], "title": "SUNRPC: close backchannel before destroying callback service", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/nfs/callback.c", "include/linux/sunrpc/bc_xprt.h", "net/sunrpc/backchannel_rqst.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "6debde9e3e6ae21dcca75837b4247b13ca4ea2b8", "status": "affected", "version": "441244d4273a8037b265fd254dfdaca5fa736ee2", "versionType": "git"}, {"lessThan": "3674f780f47d2906b5a0f7199b66973067bdfeca", "status": "affected", "version": "441244d4273a8037b265fd254dfdaca5fa736ee2", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/nfs/callback.c", "include/linux/sunrpc/bc_xprt.h", "net/sunrpc/backchannel_rqst.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.19"}, {"lessThan": "6.19", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: close backchannel before destroying callback service\n\nA backchannel receive can complete a request while the NFS callback\nservice is being torn down. xprt_complete_bc_request() removes the\nrequest from bc_pa_list, drops bc_alloc_count, marks the request in use,\nand then asks xprt_enqueue_bc_request() to hand it to the callback\nservice.\n\nIf teardown has already cleared xprt->bc_serv, xprt_enqueue_bc_request()\ncurrently returns without enqueueing or freeing the committed request.\nThe xprt_get() taken on entry is leaked as well. If the producer wins\nthe race before bc_serv is cleared, it can also enqueue onto sv_cb_list\nafter nfs_callback_down() has stopped the callback threads, leaving the\nrequest linked to a svc_serv that is about to be freed.\n\nClose the producer side before callback threads are stopped. Add\nxprt_svc_shutdown_bc() to clear xprt->bc_serv under bc_pa_lock, and call\nit on callback shutdown and callback-start failure before stopping the\nservice threads. Requests that lose the NULL transition in\nxprt_enqueue_bc_request() are released through the normal backchannel\nfree path after balancing bc_slot_count. Finally, drain any remaining\nsv_cb_list requests after the callback threads have stopped and before\nsvc_destroy() frees the service."}], "id": "CVE-2026-89546", "lastModified": "2026-10-19T09:17:49.723", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-11T20:19:37.960", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3674f780f47d2906b5a0f7199b66973067bdfeca"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6debde9e3e6ae21dcca75837b4247b13ca4ea2b8"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux Kernel: Resource management flaw in SUNRPC NFS callback service", "id": "2532175", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532175"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-911", "details": ["A flaw was found in the Linux kernel's SUNRPC (Sun Remote Procedure Call) Network File System (NFS) callback service. A race condition during the service teardown can lead to system resources not being properly released, causing a resource leak. This issue could also result in a use-after-free vulnerability, where the system attempts to access memory that has already been deallocated. An attacker could potentially exploit this vulnerability to cause a denial of service, making the affected system unstable or unresponsive."], "name": "CVE-2026-89546", "public_date": "2026-09-11T19:44:21Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89546\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89546\nhttps://git.kernel.org/stable/c/3674f780f47d2906b5a0f7199b66973067bdfeca\nhttps://git.kernel.org/stable/c/6debde9e3e6ae21dcca75837b4247b13ca4ea2b8"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[441244d4273a8037b265fd254dfdaca5fa736ee2,6debde9e3e6ae21dcca75837b4247b13ca4ea2b8)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[441244d4273a8037b265fd254dfdaca5fa736ee2,3674f780f47d2906b5a0f7199b66973067bdfeca)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "6.19"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.19)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.4,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T03:30:08.482035+00:00", "updated": "2026-09-15T22:45:07.197235+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"], "weaknesses": ["CWE-911"]}