SB20261022205 - Out-of-bounds write in Linux kernel net

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Main Vulnerability Database SB20261022205

SB20261022205 - Out-of-bounds write in Linux kernel net

Published: October 22, 2026

Security Bulletin ID SB20261022205
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Denial of service

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Out-of-bounds write (CVE-ID: CVE-2026-98621)

CWE-ID: CWE-787 - Out-of-bounds write

CVSSv4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to corrupt kernel memory and potentially cause a denial of service.

The vulnerability exists due to an integer underflow leading to an out-of-bounds write in the Linux kernel's GUE REMCSUM processing when the checksum field offset is less than the checksum start offset. A remote attacker can send a specially crafted GUE packet to underflow the checksum offset stored in skb->csum_offset and trigger a two-byte write approximately 64 KiB beyond the destination buffer if the forwarded packet retains CHECKSUM_PARTIAL and reaches a NETIF_F_HW_CSUM driver that trusts this metadata.


Remediation

Install update from vendor's website.

References