{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89544", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.722Z", "datePublished": "2026-09-11T19:44:20.424Z", "dateUpdated": "2026-10-21T12:47:49.203Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:47:49.203Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: fix gssx_dec_option_array error path bugs\n\nFour coupled defects in the gssx XDR option-array decoder make the\nerror paths unsafe: a NULL deref in the caller, a refcount leak on\nthe decoded group_info, and a latent use-after-free that the leak\nfix would otherwise expose.\n\ngssx_dec_option_array() sets oa->count = 1 before allocating\noa->data. If that allocation fails, -ENOMEM is returned with\noa->count == 1 and oa->data == NULL. All other error paths jump\nto free_oa: which frees oa->data and NULLs it but also leaves\noa->count == 1. The caller trusts the count:\n\n gssp_accept_sec_context_upcall()\n gssx_dec_accept_sec_context()\n gssx_dec_option_array() /* fails, count=1 data=NULL */\n data = res.options.data[0].value /* NULL deref */\n\nIndependently, free_creds: releases the partially decoded svc_cred\nwith a bare kfree(creds). gssx_dec_linux_creds() installs a\ngroups_alloc() result into creds->cr_group_info; that object is\nkvmalloc-backed and refcounted, and only put_group_info() reaches\nkvfree(). A plain kfree(creds) drops the wrapper and leaks the\ngroup_info allocation.\n\nThe natural fix for the leak is to call free_svc_cred(creds) before\nkfree(creds), but free_svc_cred() invokes put_group_info() on\ncreds->cr_group_info unconditionally when non-NULL. The existing\nout_free_groups: path in gssx_dec_linux_creds() already called\ngroups_free() on that pointer without clearing it, so once\nfree_svc_cred() is wired in, the subsequent put_group_info() would\ntouch freed memory.\n\nFix all four together:\n\n - Move the oa->count = 1 assignment below the oa->data allocation\n so it is never set when oa->data is NULL.\n - Reset oa->count to 0 at free_oa: so count and data stay\n coherent and the caller sees an empty option array.\n - Call free_svc_cred(creds) before kfree(creds) at free_creds:\n so the refcounted cr_group_info is released. free_svc_cred()\n either NULL-guards each field explicitly (cr_group_info has\n an if() check) or delegates to a helper that is NULL-safe\n itself (kfree for the string fields, gss_mech_put() which\n guards with if(gm) at gss_mech_switch.c:342), so it is safe\n to call on a partially decoded svc_cred where only\n cr_uid/cr_gid/cr_group_info have been written and everything\n else is zero from kzalloc.\n - In gssx_dec_linux_creds()'s out_free_groups: path, release\n cr_group_info with put_group_info() rather than groups_free()\n so the teardown matches free_svc_cred()'s refcount-aware path,\n and clear the pointer so a later free_svc_cred() on the same\n creds does not release it a second time." } ], "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 decoder runs only as a consequence of an RPCSEC_GSS_INIT/CONTINUE_INIT Call to in-kernel nfsd (and other SUNRPC servers such as lockd) on the network, typically TCP/2049. A remote client drives svcauth_gss_proxy_init() → gssp_accept_sec_context_upcall() → gssx_dec_option_array(); the attacker’s reach is purely over the network.\nAC:L - Any allocation or XDR error after oa->count is set to 1 leaves count=1 with data=NULL, and the caller always indexes res.options.data[0]. The attacker can induce those failures by flooding pre-auth GSS_INIT upcalls that each pin 256 KB of receive pages (especially under memcg-limited nfsd) and by driving large group-list replies, so success does not depend on conditions beyond their control.\nPR:N - svcauth_gss_proxy_init() runs from svcauth_gss_proc_init() on the first RPCSEC_GSS handshake leg, before the kernel has validated any Kerberos ticket. The upcall and option-array decode execute for an unauthenticated NFS client; no local account or prior credential on the server is required.\nUI:N - The crash is triggered entirely by an inbound RPC to an already-running nfsd/SUNRPC service thread. No administrator or end-user action such as mounting a filesystem or opening a file is required.\nS:U - The NULL dereference and group_info leak occur inside the host kernel’s SUNRPC/GSS code. Impact stays within that kernel’s security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - With oa->count==1 and oa->data==NULL, gssp_accept_sec_context_upcall() does &res.options.data[0].value, a NULL+small-offset load that faults on the unmapped zero page. No kernel memory is returned to the attacker; unlike a UAF, freed object contents are never read.\nI:N - The faulting access is a pure NULL-pointer dereference with no kernel write. The put_group_info() UAF described in the fix is only latent: the unpatched free_creds path kfree()s the svc_cred wrapper without touching cr_group_info, so the dangling pointer is not used.\nA:H - The NULL dereference oopses the nfsd (or lockd) thread and panics the host where panic_on_oops is set, which is typical on NAS/appliance NFS servers. The same error path also leaks the kvmalloc-backed group_info, and the crash can be repeated to take down SUNRPC service threads." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sunrpc/auth_gss/gss_rpc_xdr.c" ], "versions": [ { "version": "5e6013ae2c8d420faea553d363935f65badd32c3", "lessThan": "8c56a46db3b7523f13e167c3e2c6e3c47a87dcb3", "status": "affected", "versionType": "git" }, { "version": "3cfcfc102a5e57b021b786a755a38935e357797d", "lessThan": "fb30241f7ccace372ee83017891549f23a715581", "status": "affected", "versionType": "git" }, { "version": "3cfcfc102a5e57b021b786a755a38935e357797d", "lessThan": "3ff45361e9469e85c0f86b8e7b82c63e50bab8ef", "status": "affected", "versionType": "git" }, { "version": "3cfcfc102a5e57b021b786a755a38935e357797d", "lessThan": "f85a83774d7f4e2ac71c0c384df0dfb6f7d0179a", "status": "affected", "versionType": "git" }, { "version": "3cfcfc102a5e57b021b786a755a38935e357797d", "lessThan": "5e9a94539b1ec17a89177d952badfd0d844d694a", "status": "affected", "versionType": "git" }, { "version": "b97c37978ca825557d331c9012e0c1ddc0e42364", "status": "affected", "versionType": "git" }, { "version": "bfa9d86d39a0fe4685f90c3529aa9bd62a9d97a8", "status": "affected", "versionType": "git" }, { "version": "bb336cd8d5ecb69c430ebe3e7bcff68471d93fa8", "status": "affected", "versionType": "git" }, { "version": "dd292e884c649f9b1c18af0ec75ca90b390cd044", "status": "affected", "versionType": "git" }, { "version": "934212a623cbab851848b6de377eb476718c3e4c", "status": "affected", "versionType": "git" }, { "version": "9806c2393cd2ab0a8e7bb9ffae02ce20e3112ec4", "status": "affected", "versionType": "git" }, { "version": "996997d1fb2126feda550d6adcedcbd94911fc69", "status": "affected", "versionType": "git" }, { "version": "6.6.23", "lessThan": "6.6.160", "status": "affected", "versionType": "semver" }, { "version": "4.19.311", "lessThan": "4.20", "status": "affected", "versionType": "semver" }, { "version": "5.4.273", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "5.10.214", "lessThan": "5.11", "status": "affected", "versionType": "semver" }, { "version": "5.15.153", "lessThan": "5.16", "status": "affected", "versionType": "semver" }, { "version": "6.1.83", "lessThan": "6.2", "status": "affected", "versionType": "semver" }, { "version": "6.7.11", "lessThan": "6.8", "status": "affected", "versionType": "semver" }, { "version": "6.8.2", "lessThan": "6.9", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sunrpc/auth_gss/gss_rpc_xdr.c" ], "versions": [ { "version": "6.9", "status": "affected" }, { "version": "0", "lessThan": "6.9", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.51", "lessThanOrEqual": "6.18.*", "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": "6.6.23", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.18.51" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.311" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.273" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.214" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.153" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.83" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8c56a46db3b7523f13e167c3e2c6e3c47a87dcb3" }, { "url": "https://git.kernel.org/stable/c/fb30241f7ccace372ee83017891549f23a715581" }, { "url": "https://git.kernel.org/stable/c/3ff45361e9469e85c0f86b8e7b82c63e50bab8ef" }, { "url": "https://git.kernel.org/stable/c/f85a83774d7f4e2ac71c0c384df0dfb6f7d0179a" }, { "url": "https://git.kernel.org/stable/c/5e9a94539b1ec17a89177d952badfd0d844d694a" } ], "title": "SUNRPC: fix gssx_dec_option_array error path bugs", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-89544", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:23:33.519592Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:42.511Z" } } ] } }