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TI-2026-60681 Aliases CVE-2026-89638GHSA-7hx7-9jhj-445w

smb: client: clear setuid/setgid bit on write with cifsacl/modefromsid/posix extensions

Priority LOW 35Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 16 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: clear setuid/setgid bit on write with cifsacl/modefromsid/posix extensions When a file has the setuid or setgid bit set and is written to, the VFS strips those bits and issues a setattr with ATTR_KILL_SUID/ATTR_KILL_SGID together with an ATTR_MODE carrying the already-cleared mode. Both cifs_setattr_unix() and cifs_setattr_nounix() unconditionally dropped ATTR_MODE in that case: /* skip mode change if it's just for clearing setuid/setgid */ if (attrs->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) attrs->ia_valid &= ~ATTR_MODE; This is fine for the default mount, where the mode is only emulated via the DOS read-only attribute and cannot represent the setuid/setgid bits anyway. However, with the "cifsacl" or "modefromsid" mount options the mode is stored on the server through an ACL (id_mode_to_cifs_acl()), with the SMB3.1.1 POSIX extensions the mode is sent to the server directly, and with the SMB1 Unix extensions (cifs_setattr_unix) the mode is sent via CIFSSMBUnixSetPathInfo(). In all those cases dropping ATTR_MODE means the cleared mode is never pushed to the server, so the setuid/setgid bit survives the write. This is a security issue: on local filesystems the setuid bit is stripped when a file is written, but over these cifs.ko mounts the bit persists on the server, potentially allowing an unexpected privilege escalation on subsequent execution. Fix this in two places: 1. cifs_setattr_nounix(): only take the "skip mode change" shortcut when the mode is emulated via the DOS read-only attribute (i.e. neither cifsacl/modefromsid nor the SMB3.1.1 POSIX extensions are in effect), so that the cleared mode is propagated to the server in the ACL / POSIX cases. 2. cifs_setattr_unix(): this function is only called when Unix extensions are in effect, so the mode is always stored on the server. Remove the shortcut entirely so that the cleared mode is always pushed.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00178 7th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.10.273, 5.15.224, 6.1.191 +5Red Hat: 4 advisoriesRed Hat: 16 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux2.6.24 and later5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.51, 7.2.4, 7.3Patch availableCNA
  • Linux VendorLinux Affected 2.6.24 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.51, 7.2.4, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.51, 7.2.4, 7.3

Red Hat 4 advisories

  • RHSA-2026:91565 Released 2026-10-28 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • 10Base-SMTV kernel-modules-internal-6.12.0-211.69.1.el10_2
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.69.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.69.1.el10_2, kernel-64k-devel-6.12.0-211.69.1.el10_2 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-211.69.1.el10_2, kernel-64k-6.12.0-211.69.1.el10_2, kernel-64k-core-6.12.0-211.69.1.el10_2 +29
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.69.1.el10_2, libperf-6.12.0-211.69.1.el10_2
    • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal-6.12.0-211.69.1.el10_2
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-211.69.1.el10_2, kernel-rt-64k-6.12.0-211.69.1.el10_2, kernel-rt-64k-core-6.12.0-211.69.1.el10_2 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-211.69.1.el10_2, kernel-rt-core-6.12.0-211.69.1.el10_2, kernel-rt-debug-6.12.0-211.69.1.el10_2 +9
  • RHSA-2026:90365 Released 2026-10-26 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-687.61.1.el9_8, kernel-64k-debug-devel-matched-5.14.0-687.61.1.el9_8, kernel-64k-devel-5.14.0-687.61.1.el9_8 +12
    • Red Hat Enterprise Linux BaseOS (v. 9) kernel-5.14.0-687.61.1.el9_8, kernel-64k-5.14.0-687.61.1.el9_8, kernel-64k-core-5.14.0-687.61.1.el9_8 +28
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-687.61.1.el9_8, libperf-5.14.0-687.61.1.el9_8
    • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-687.61.1.el9_8, kernel-rt-64k-5.14.0-687.61.1.el9_8, kernel-rt-64k-core-5.14.0-687.61.1.el9_8 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-687.61.1.el9_8, kernel-rt-core-5.14.0-687.61.1.el9_8, kernel-rt-debug-5.14.0-687.61.1.el9_8 +9
  • RHSA-2026:89083 Released 2026-10-24 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-553.178.1.el8_10, kernel-4.18.0-553.178.1.el8_10, kernel-abi-stablelists-4.18.0-553.178.1.el8_10 +19
    • Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-553.178.1.el8_10
Show 1 more Red Hat advisories
  • RHSA-2026:89082 Released 2026-10-24 · Red Hat rating Important
    kernel-rt security, bug fix, and enhancement update
    • Red Hat Enterprise Linux NFV (v. 8) kernel-rt-4.18.0-553.178.1.rt7.519.el8_10, kernel-rt-core-4.18.0-553.178.1.rt7.519.el8_10, kernel-rt-debug-4.18.0-553.178.1.rt7.519.el8_10 +9
    • Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-553.178.1.rt7.519.el8_10, kernel-rt-core-4.18.0-553.178.1.rt7.519.el8_10, kernel-rt-debug-4.18.0-553.178.1.rt7.519.el8_10 +7

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 9AffectedNo fix yet
10Base-SMTVFixed RHSA-2026:91565
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:91565
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:90365
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:91565
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2026:89083
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2026:90365
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:89083
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:91565
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:90365
Red Hat Enterprise Linux Hidden (v. 10)Fixed RHSA-2026:91565
Red Hat Enterprise Linux NFV (v. 8)Fixed RHSA-2026:89082
Red Hat Enterprise Linux RT (v. 8)Fixed RHSA-2026:89082
Red Hat Enterprise Linux Real Time (v. 10)Fixed RHSA-2026:91565
Red Hat Enterprise Linux Real Time (v. 9)Fixed RHSA-2026:90365
Red Hat Enterprise Linux Real Time for NFV (v. 10)Fixed RHSA-2026:91565
Red Hat Enterprise Linux Real Time for NFV (v. 9)Fixed RHSA-2026:90365
Not affected: 2 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-89638
  2. 2026-10-03 Alias added: GHSA-7hx7-9jhj-445w
  3. 2026-10-16 Fix available: Linux/Linux@58b23fc9fb580432470d6c5da3c1e5660dba9fbc, Linux/[email protected] · CNA
  4. 2026-10-16 1 new reference · CNA
  5. 2026-10-18 CISA SSVC decision points changed
  6. 2026-10-19 Fix available: Linux/[email protected] · CNA
  7. 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@7ceb6f7cb8f8f2b094e0dcdaf75757775d231378 · CNA
  8. 2026-10-21 1 new reference · CNA
  9. 2026-10-26 Fix available: RHSA-2026:89083 · Red Hat
  10. 2026-10-26 Fix available: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) · Red Hat
  11. 2026-10-26 Fix available: RHSA-2026:89082 · Red Hat
  12. 2026-10-26 Fix available: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8) · Red Hat
  13. 2026-10-27 Fix available: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) +2 · Red Hat
  14. 2026-10-29 Fix available: 10Base-SMTV, Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) +4 · Red Hat
  15. 2026-10-29 Fix available: RHSA-2026:90365 · Red Hat
  16. 2026-10-29 Fix available: RHSA-2026:91565 · Red Hat
  17. 2026-10-30 Fix available: Linux/Linux@2a5206992f526178881e8f5c4644757c336fb76d, Linux/[email protected], Linux/[email protected] +3 · CNA
  18. 2026-10-30 3 new references · CNA

References

Other 8

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences