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TI-2026-60674 Aliases CVE-2026-89631GHSA-95qf-fgcq-pcrc

smb: client: reject a tree connect response whose byte count is too small

Priority MEDIUM 46Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · None · High
Fix status
Partial Red Hat: 11 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: reject a tree connect response whose byte count is too small CIFSTCon() bounds its strnlen() over the byte area with the server's ByteCount minus two, which for ByteCount 0 or 1 goes negative as an int and converts to a huge size_t. The later subtraction wraps the __u16 bytes_left, and that is what bounds cifs_strndup_from_utf16(): a bound of up to 65535 against a ~16 KB cifs_req_poolp object runs off the end of the slab object, and the bytes reach userspace through tcon->nativeFileSystem in /proc/fs/cifs/DebugData. Reject a byte area too small for what the parser consumes. Two bytes is the least it can consume, and no conformant response carries fewer. The new trace point is the 129th smb_eio_trace entry, which __mode(byte) cannot represent, so the attribute goes with it.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00491 42nd percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.1.191, 6.6.160, 6.12.114 +3Red Hat: 3 advisoriesRed Hat: 11 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

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

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux2.6.30 and later6.1.191, 6.6.160, 6.12.114, 6.18.51, 7.2.4, 7.3Patch availableCNA
  • Linux VendorLinux Affected 2.6.30 and later Fixed in 6.1.191, 6.6.160, 6.12.114, 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 6.1.191, 6.6.160, 6.12.114, 6.18.51, 7.2.4, 7.3

Red Hat 3 advisories

  • RHSA-2026:85773 Released 2026-10-20 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-553.176.1.el8_10, kernel-4.18.0-553.176.1.el8_10, kernel-abi-stablelists-4.18.0-553.176.1.el8_10 +19
    • Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-553.176.1.el8_10
  • RHSA-2026:85774 Released 2026-10-20 · Red Hat rating Important
    kernel-rt security, bug fix, and enhancement update
    • Red Hat Enterprise Linux NFV (v. 8) kernel-rt-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-core-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-debug-4.18.0-553.176.1.rt7.517.el8_10 +9
    • Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-core-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-debug-4.18.0-553.176.1.rt7.517.el8_10 +7
  • RHSA-2026:85321 Released 2026-10-19 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • 10Base-SMTV kernel-modules-internal-6.12.0-211.67.1.el10_2
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.67.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.67.1.el10_2, kernel-64k-devel-6.12.0-211.67.1.el10_2 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-211.67.1.el10_2, kernel-64k-6.12.0-211.67.1.el10_2, kernel-64k-core-6.12.0-211.67.1.el10_2 +29
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.67.1.el10_2, libperf-6.12.0-211.67.1.el10_2
    • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal-6.12.0-211.67.1.el10_2
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-211.67.1.el10_2, kernel-rt-64k-6.12.0-211.67.1.el10_2, kernel-rt-64k-core-6.12.0-211.67.1.el10_2 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-211.67.1.el10_2, kernel-rt-core-6.12.0-211.67.1.el10_2, kernel-rt-debug-6.12.0-211.67.1.el10_2 +9

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-2026:85321
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2026:85773
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:85773
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux Hidden (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux NFV (v. 8)Fixed RHSA-2026:85774
Red Hat Enterprise Linux RT (v. 8)Fixed RHSA-2026:85774
Red Hat Enterprise Linux Real Time (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux Real Time for NFV (v. 10)Fixed RHSA-2026:85321
Not affected: 2 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-89631
  2. 2026-10-03 Alias added: GHSA-95qf-fgcq-pcrc
  3. 2026-10-18 CISA SSVC decision points changed
  4. 2026-10-19 Fix available: Linux/[email protected] · CNA
  5. 2026-10-20 Fix available: RHSA-2026:85321 · Red Hat
  6. 2026-10-20 Fix available: RHSA-2026:85773 · Red Hat
  7. 2026-10-20 Fix available: RHSA-2026:85774 · Red Hat
  8. 2026-10-20 Fix available: 10Base-SMTV, Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) +8 · Red Hat
  9. 2026-10-21 Fix available: Linux/Linux@2ae219762ebac929bf6ab3473681f10ed566af08, Linux/[email protected], Linux/[email protected] +1 · CNA
  10. 2026-10-21 2 new references · CNA
  11. 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@bb99866cb1d3d5e8201200a8692fd8da3106a8fd · CNA
  12. 2026-10-30 1 new reference · CNA

References

Other 6

  • 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