CVE-2026-98171

smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs

HIGH
8.8
CVSS Score
Published: October 6, 2026 at 08:44 AM UTC
Updated: October 30, 2026 at 01:21 PM UTC
1 product affected across 1 vendorLinux Kernel

Using Linux by Linux?

Get instant alerts when new vulnerabilities affect Linux - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
HIGH8.8
Exploit prediction
EPSS 0.5%

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs Fix several related bounds checking and pointer lifecycle issues in receive_encrypted_standard()'s handling of compound encrypted frames: - Clear next_buffer after assigning it to server->bigbuf. A stale next_buffer pointer can lead to a use-after-free on subsequent error paths. - Update pdu_length to the decrypted plaintext size (buf_size). Using the pre-decryption length allows NextCommand to point into stale ciphertext residue. - Reject next_cmd values smaller than MID_HEADER_SIZE(server). - Fix an integer overflow in the upper bound check by verifying pdu_length - next_cmd < MID_HEADER_SIZE(server), ensuring the trailing slice is large enough for a header.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Vendor states this is fixed in 4.19 (unaffected)
Vendor states this is fixed in 6.1.* (unaffected)
Vendor states this is fixed in 6.1.189 (unaffected)
Vendor states this is fixed in 6.12.* (unaffected)
Vendor states this is fixed in 6.12.112 (unaffected)
Vendor states this is fixed in 6.18.* (unaffected)
Vendor states this is fixed in 6.18.54 (unaffected)
Vendor states this is fixed in 6.6.* (unaffected)
Vendor states this is fixed in 6.6.158 (unaffected)
Vendor states this is fixed in 7.2.* (unaffected)
Vendor states this is fixed in 7.2.8 (unaffected)
Vendor states this is fixed in 7.3 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

CVSS

8.8HIGHLinux
Vector?

Quick Info

StatusRECEIVED

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card