Incorrect Calculation of Buffer Size in Linux kernel - CVE-2026-74657
Published: August 24, 2026
Vulnerability identifier: #VU144852
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-74657
CWE-ID: CWE-131
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper calculation of buffer size in fib_nlmsg_size() in the IPv4 routing subsystem when generating route notifications for nexthops that use RTA_VIA. A local user can trigger route notification handling involving an IPv6 gateway to cause a denial of service.
The issue can reach a kernel panic if panic_on_warn is set.
Affected software
Linux kernel
Debian Linux
linux (Debian package)
Debian Linux
linux (Debian package)
How to mitigate CVE-2026-74657
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
linux (Debian package) - update to 6.12.105-1
linux (Debian package) - update to 6.12.105-1
External References
- https://git.kernel.org/stable/c/0f0ca602941d0a81ae9514943ca06c55159c6385
- https://git.kernel.org/stable/c/4a5dfbae5179f6574695012a980476254df2d295
- https://git.kernel.org/stable/c/4ff9548d84945d2cbf9e4c207288063a200ea397
- https://git.kernel.org/stable/c/5307a53599fa762c06e475ee4a375252074fd324
- https://git.kernel.org/stable/c/7f80ad373ce4a7af5367ff273cea0f16e91387f3
- https://git.kernel.org/stable/c/9b22f13524fa0de0d963bbd3002df6c28bae3395
- https://git.kernel.org/stable/c/a59edda6eda1252340354322d8ab318b2e9052fb