Linux kernel SMB client: wrong total_read for compound encrypted PDUs
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 5 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel SMB client leaves server->total_read at the full decrypted frame size when it walks sub-PDUs of a compound encrypted frame in receive_encrypted_standard(). cifs_handle_standard() then passes that full size to smb2_check_message(), so the PDU length guards validate the whole compound frame instead of the current sub-PDU. A truncated non-last sub-PDU can bypass length validation and cause out-of-bounds reads in smb2_get_data_area_len(). Red Hat rates it Moderate, and the sources list no fixed version for Red Hat Enterprise Linux 8, 9 and 10 or OpenShift Container Platform 4 and 5.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix server->total_read for compound encrypted PDUs In receive_encrypted_standard(), server->total_read is left at the full decrypted frame size when walking sub-PDUs of a compound encrypted frame. As a result, cifs_handle_standard() passes this full size to smb2_check_message(), causing the PDU length guards to incorrectly validate the entire compound frame instead of the current sub-PDU. This allows truncated non-last sub-PDUs to bypass length validation, leading to out-of-bounds reads in smb2_get_data_area_len(). Fix this by setting server->total_read to the true length of the current sub-PDU: next_cmd for non-last sub-PDUs, and the remaining pdu_length for the last one.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Upgrade to a fixed Linux kernel release: 6.1.189, 6.6.158, 6.12.112, 6.18.54, 7.2.8 or 7.3. Kernels from 4.19 onward are affected until they receive the fix.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.1.189, 6.6.158, 6.12.112, 6.18.54, 7.2.8, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-06 Threatist record created from CVE-2026-98167
- 2026-10-06 Alias added: GHSA-wwfg-4wrm-v6qx
- 2026-10-07 Affected versions changed · Red Hat
- 2026-10-07 CVSS score added · Red Hat
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-20 CVSS score changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
Other 6
- https://git.kernel.org/stable/c/8703539d22fdbc13dd2db090ee199c3a427b8ea0
- https://git.kernel.org/stable/c/e78fc1d240b27349b45a0f1c3e3c2c401d7e230d
- https://git.kernel.org/stable/c/a46eb242e9eef3a3897d166748b23303c516e870
- https://git.kernel.org/stable/c/ebb8a075fdc7af3d196a4f158a0e18dbc394c0e3
- https://git.kernel.org/stable/c/282b72f9a7ef31296c48366db4128882999cc048
- https://git.kernel.org/stable/c/f73726b83e4756fdaa099e1bc1143293bd57ad79
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Sources
- CVE-2026-98167 · CVE Program
- CVE-2026-98167 · NVD
- FIRST EPSS
- GHSA-wwfg-4wrm-v6qx · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98167 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences