Integer underflow in Linux kernel - CVE-2026-89551
Published: September 12, 2026
Vulnerability identifier: #VU149256
CSH Severity: Low
CVSS v4: 0 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89551
CWE-ID: CWE-191
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause downstream XDR decoders to use an incorrect stream bound.
The vulnerability exists due to an integer underflow in xdr_buf_trim() when processing GSS Kerberos v2 data whose recorded buffer length is smaller than the associated I/O vector lengths. A remote attacker can cause xdr_buf_trim() to consume more bytes than buf->len records to cause downstream XDR decoders to use an incorrect stream bound.
Affected software
Linux kernel
How to mitigate CVE-2026-89551
Install security update from vendor's repository.