{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31709","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-03-09T15:48:24.133Z","datePublished":"2026-05-01T13:56:06.522Z","dateUpdated":"2026-06-30T12:07:48.234Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-06-19T11:57:57.204Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: validate the whole DACL before rewriting it in cifsacl\n\nbuild_sec_desc() and id_mode_to_cifs_acl() derive a DACL pointer from a\nserver-supplied dacloffset and then use the incoming ACL to rebuild the\nchmod/chown security descriptor.\n\nThe original fix only checked that the struct smb_acl header fits before\nreading dacl_ptr->size or dacl_ptr->num_aces.  That avoids the immediate\nheader-field OOB read, but the rewrite helpers still walk ACEs based on\npdacl->num_aces with no structural validation of the incoming DACL body.\n\nA malicious server can return a truncated DACL that still contains a\nheader, claims one or more ACEs, and then drive\nreplace_sids_and_copy_aces() or set_chmod_dacl() past the validated\nextent while they compare or copy attacker-controlled ACEs.\n\nFactor the DACL structural checks into validate_dacl(), extend them to\nvalidate each ACE against the DACL bounds, and use the shared validator\nbefore the chmod/chown rebuild paths.  parse_dacl() reuses the same\nvalidator so the read-side parser and write-side rewrite paths agree on\nwhat constitutes a well-formed incoming DACL."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"}}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/cifsacl.c"],"versions":[{"version":"bc3e9dd9d104ca1b75644eab87b38ce8a924aef4","lessThan":"b8603d9ae6c9087662b098619996bc4a8064319d","status":"affected","versionType":"git"},{"version":"bc3e9dd9d104ca1b75644eab87b38ce8a924aef4","lessThan":"c2abdebf72000a64603ced84d36ccbd164f11391","status":"affected","versionType":"git"},{"version":"bc3e9dd9d104ca1b75644eab87b38ce8a924aef4","lessThan":"8e47d297e7cf9a6029a0d38e7b22faba7d7aaf12","status":"affected","versionType":"git"},{"version":"bc3e9dd9d104ca1b75644eab87b38ce8a924aef4","lessThan":"d92f3f0b22414e7515696a02224d0af55e3004a3","status":"affected","versionType":"git"},{"version":"bc3e9dd9d104ca1b75644eab87b38ce8a924aef4","lessThan":"ff0ca46b13b9ef6edbcd238a3b6caacfef8ba0e5","status":"affected","versionType":"git"},{"version":"bc3e9dd9d104ca1b75644eab87b38ce8a924aef4","lessThan":"b78db9bddc84136f6a0bb49e8883cf200dfb87a8","status":"affected","versionType":"git"},{"version":"bc3e9dd9d104ca1b75644eab87b38ce8a924aef4","lessThan":"0a8cf165566ba55a39fd0f4de172119dd646d39a","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/smb/client/cifsacl.c"],"versions":[{"version":"5.12","status":"affected"},{"version":"0","lessThan":"5.12","status":"unaffected","versionType":"semver"},{"version":"5.15.210","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.176","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.140","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.86","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.35","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.2","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":"5.12","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.6.140"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.12.86"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.0.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/b8603d9ae6c9087662b098619996bc4a8064319d"},{"url":"https://git.kernel.org/stable/c/c2abdebf72000a64603ced84d36ccbd164f11391"},{"url":"https://git.kernel.org/stable/c/8e47d297e7cf9a6029a0d38e7b22faba7d7aaf12"},{"url":"https://git.kernel.org/stable/c/d92f3f0b22414e7515696a02224d0af55e3004a3"},{"url":"https://git.kernel.org/stable/c/ff0ca46b13b9ef6edbcd238a3b6caacfef8ba0e5"},{"url":"https://git.kernel.org/stable/c/b78db9bddc84136f6a0bb49e8883cf200dfb87a8"},{"url":"https://git.kernel.org/stable/c/0a8cf165566ba55a39fd0f4de172119dd646d39a"}],"title":"smb: client: validate the whole DACL before rewriting it in cifsacl","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"cpes":["cpe:/o:redhat:enterprise_linux_eus:10.0"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux AppStream EUS (v. 10.0)","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:10.2"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux AppStream (v. 10)","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:rhel_e4s:9.2::appstream"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux AppStream E4S (v.9.2)","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:rhel_e4s:9.4::appstream"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux AppStream E4S (v.9.4)","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:rhel_eus:9.6::appstream"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux AppStream EUS (v.9.6)","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:enterprise_linux:9::appstream"],"defaultStatus":"affected","product":"Red 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Hat"},{"cpes":["cpe:/a:redhat:rhel_eus:9.6::realtime"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux Real Time EUS (v.9.6)","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:enterprise_linux:9::realtime"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux Real Time (v. 9)","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":"2026-05-01T00:00:00.000Z","descriptions":[{"lang":"en","value":"A flaw was found in the Linux kernel's Server Message Block (SMB) client, specifically within the cifsacl functionality. A malicious SMB server could provide a malformed Discretionary Access Control List (DACL) that claims to contain more Access Control Entries (ACEs) than are actually present. This insufficient validation allows the kernel to read or copy data beyond the intended memory boundaries, leading to memory corruption. This could potentially result in information disclosure or a denial of service."}],"metrics":[{"other":{"content":{"namespace":"https://access.redhat.com/security/updates/classification/","value":"Important"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7.8,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1288","description":"Improper Validation of Consistency within Input","lang":"en","type":"CWE"}]}],"references":[{"tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-31709"},{"name":"RHBZ#2464476","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2464476"},{"tags":["x_sadp-csaf-vex"],"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31709.json"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:24343"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:23329"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:22940"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:23237"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:23224"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:21556"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:21706"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:21745"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:22900"}],"solutions":[{"lang":"en","value":"RHSA-2026:24343: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0), Red Hat Enterprise Linux Real Time EUS (v. 10.0), Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0)"},{"lang":"en","value":"RHSA-2026:23329: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10)"},{"lang":"en","value":"RHSA-2026:22940: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux BaseOS E4S (v.9.2)"},{"lang":"en","value":"RHSA-2026:23237: Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux BaseOS E4S (v.9.4), Red Hat Enterprise Linux Real Time E4S (v.9.4), Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4)"},{"lang":"en","value":"RHSA-2026:23224: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat Enterprise Linux BaseOS EUS (v.9.6), Red Hat Enterprise Linux Real Time EUS (v.9.6), Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6)"},{"lang":"en","value":"RHSA-2026:21556: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9)"},{"lang":"en","value":"RHSA-2026:21706: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8)"},{"lang":"en","value":"RHSA-2026:21745: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8)"},{"lang":"en","value":"RHSA-2026:22900: Red Hat Enterprise Linux Real Time E4S (v.9.2), Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)"}],"timeline":[{"lang":"en","time":"2026-05-01T00:00:00.000Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-05-01T00:00:00.000Z","value":"Made public."}],"title":"kernel: smb: client: validate the whole DACL before rewriting it in cifsacl","workarounds":[{"lang":"en","value":"To mitigate this issue, if SMB client functionality is not required, the `cifs` kernel module can be blacklisted to prevent it from loading. This can be achieved by creating a modprobe configuration file.\n\n1. Create a file named `/etc/modprobe.d/disable-cifs.conf` with the following content:\n   ```\n   install cifs /bin/true\n   blacklist cifs\n   ```\n2. Regenerate the initramfs to ensure the change takes effect on boot:\n   ```bash\n   dracut -f -v\n   ```\n   or for systems using `mkinitrd`:\n   ```bash\n   mkinitrd -f /boot/initramfs-$(uname -r).img $(uname -r)\n   ```\n3. A system reboot is required for the changes to take effect.\n\nWarning: Disabling the `cifs` module will prevent the system from mounting SMB/CIFS shares. Ensure this functionality is not critical before applying this mitigation.\n\nrefer: https://access.redhat.com/solutions/4117281"}],"x_adpType":"supplier","x_generator":{"engine":"sadp-cli 1.0.0"},"providerMetadata":{"orgId":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","shortName":"redhat-SADP","dateUpdated":"2026-06-30T12:07:48.234Z"}}]}}