{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-52991","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-06-09T07:44:35.377Z","datePublished":"2026-06-24T16:29:04.810Z","dateUpdated":"2026-06-30T12:09:39.972Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-06-28T06:37:44.993Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/psi: fix race between file release and pressure write\n\nA potential race condition exists between pressure write and cgroup file\nrelease regarding the priv member of struct kernfs_open_file, which\ntriggers the uaf reported in [1].\n\nConsider the following scenario involving execution on two separate CPUs:\n\n   CPU0\t\t\t\t\tCPU1\n   ====\t\t\t\t\t====\n\t\t\t\t\tvfs_rmdir()\n\t\t\t\t\tkernfs_iop_rmdir()\n\t\t\t\t\tcgroup_rmdir()\n\t\t\t\t\tcgroup_kn_lock_live()\n\t\t\t\t\tcgroup_destroy_locked()\n\t\t\t\t\tcgroup_addrm_files()\n\t\t\t\t\tcgroup_rm_file()\n\t\t\t\t\tkernfs_remove_by_name()\n\t\t\t\t\tkernfs_remove_by_name_ns()\n vfs_write()\t\t\t\t__kernfs_remove()\n new_sync_write()\t\t\tkernfs_drain()\n kernfs_fop_write_iter()\t\tkernfs_drain_open_files()\n cgroup_file_write()\t\t\tkernfs_release_file()\n pressure_write()\t\t\tcgroup_file_release()\n ctx = of->priv;\n\t\t\t\t\tkfree(ctx);\n \t\t\t\t\tof->priv = NULL;\n\t\t\t\t\tcgroup_kn_unlock()\n cgroup_kn_lock_live()\n cgroup_get(cgrp)\n cgroup_kn_unlock()\n if (ctx->psi.trigger)  // here, trigger uaf for ctx, that is of->priv\n\nThe cgroup_rmdir() is protected by the cgroup_mutex, it also safeguards\nthe memory deallocation of of->priv performed within cgroup_file_release().\nHowever, the operations involving of->priv executed within pressure_write()\nare not entirely covered by the protection of cgroup_mutex. Consequently,\nif the code in pressure_write(), specifically the section handling the\nctx variable executes after cgroup_file_release() has completed, a uaf\nvulnerability involving of->priv is triggered.\n\nTherefore, the issue can be resolved by extending the scope of the\ncgroup_mutex lock within pressure_write() to encompass all code paths\ninvolving of->priv, thereby properly synchronizing the race condition\noccurring between cgroup_file_release() and pressure_write().\n\nAnd, if an live kn lock can be successfully acquired while executing\nthe pressure write operation, it indicates that the cgroup deletion\nprocess has not yet reached its final stage; consequently, the priv\npointer within open_file cannot be NULL. Therefore, the operation to\nretrieve the ctx value must be moved to a point *after* the live kn\nlock has been successfully acquired.\n\nIn another situation, specifically after entering cgroup_kn_lock_live()\nbut before acquiring cgroup_mutex, there exists a different class of\nrace condition:\n\nCPU0: write memory.pressure               CPU1: write cgroup.pressure=0\n===========================\t\t  =============================\n\nkernfs_fop_write_iter()\n kernfs_get_active_of(of)\n pressure_write()\n   cgroup_kn_lock_live(memory.pressure)\n     cgroup_tryget(cgrp)\n     kernfs_break_active_protection(kn)\n     ... blocks on cgroup_mutex\n\n                                     \t  cgroup_pressure_write()\n                                     \t  cgroup_kn_lock_live(cgroup.pressure)\n                                     \t  cgroup_file_show(memory.pressure, false)\n                                     \t    kernfs_show(false)\n                                     \t      kernfs_drain_open_files()\n                                     \t        cgroup_file_release(of)\n                                     \t          kfree(ctx)\n                                     \t            of->priv = NULL\n                                     \t  cgroup_kn_unlock()\n\n   ... acquires cgroup_mutex\n   ctx = of->priv;        // may now be NULL\n   if (ctx->psi.trigger)  // NULL dereference\n\nConsequently, there is a possibility that of->priv is NULL, the pressure\nwrite needs to check for this.\n\nNow that the scope of the cgroup_mutex has been expanded, the original\nexplicit cgroup_get/put operations are no longer necessary, this is\nbecause acquiring/releasing the live kn lock inherently executes a\ncgroup get/put operation.\n\n[1]\nBUG: KASAN: slab-use-after-free in pressure_write+0xa4/0x210 kernel/cgroup/cgroup.c:4011\nCall Trace:\n pressure_write+0xa4/0x210 kernel/cgroup/cgroup.c:4011\n cgroup_file_write+0x36f/0x790 kernel/cgroup/cgroup.c:43\n---truncated---"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"}}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/cgroup/cgroup.c"],"versions":[{"version":"0e94682b73bfa6c44c98af7a26771c9c08c055d5","lessThan":"03dc070fa0fc3cb4068693f468ccd5f8a7e58282","status":"affected","versionType":"git"},{"version":"0e94682b73bfa6c44c98af7a26771c9c08c055d5","lessThan":"d4352c0709bfd38c752fccbde7fd72a82ac78f23","status":"affected","versionType":"git"},{"version":"0e94682b73bfa6c44c98af7a26771c9c08c055d5","lessThan":"a5b98009f16d8a5fb4a8ff9a193f5735515c38fa","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/cgroup/cgroup.c"],"versions":[{"version":"5.2","status":"affected"},{"version":"0","lessThan":"5.2","status":"unaffected","versionType":"semver"},{"version":"6.18.33","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.10","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1","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":"5.2","versionEndExcluding":"6.18.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"7.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/03dc070fa0fc3cb4068693f468ccd5f8a7e58282"},{"url":"https://git.kernel.org/stable/c/d4352c0709bfd38c752fccbde7fd72a82ac78f23"},{"url":"https://git.kernel.org/stable/c/a5b98009f16d8a5fb4a8ff9a193f5735515c38fa"}],"title":"sched/psi: fix race between file release and pressure write","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"cpes":["cpe:/o:redhat:enterprise_linux:10"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux 10","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:8"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux 8","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:9"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux 9","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:6"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 6","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:7"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 7","vendor":"Red Hat"}],"datePublic":"2026-06-24T00:00:00.000Z","descriptions":[{"lang":"en","value":"A flaw was found in the Linux kernel's Pressure Stall Information (PSI) subsystem. A race condition exists between the file release and pressure write operations, specifically concerning the `priv` member of `struct kernfs_open_file`. This can lead to a use-after-free vulnerability or a NULL dereference, potentially causing system instability or a denial of service. The issue arises when the `priv` member is deallocated during a cgroup file release while a pressure write operation attempts to access it, or when it becomes NULL before being accessed."}],"metrics":[{"other":{"content":{"namespace":"https://access.redhat.com/security/updates/classification/","value":"Important"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-367","description":"Time-of-check Time-of-use (TOCTOU) Race Condition","lang":"en","type":"CWE"}]}],"references":[{"tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-52991"},{"name":"RHBZ#2492403","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2492403"},{"tags":["x_sadp-csaf-vex"],"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52991.json"}],"timeline":[{"lang":"en","time":"2026-06-24T00:00:00.000Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-06-24T00:00:00.000Z","value":"Made public."}],"title":"kernel: sched/psi: fix race between file release and pressure write","x_adpType":"supplier","x_generator":{"engine":"sadp-cli 1.0.0"},"providerMetadata":{"orgId":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","shortName":"redhat-SADP","dateUpdated":"2026-06-30T12:09:39.972Z"}}]}}