CVE-2026-23254: net: gro: fix outer network offset
In the Linux kernel, the following vulnerability has been resolved:
net: gro: fix outer network offset
The udp GRO complete stage assumes that all the packets inserted the RX have the encapsulation flag zeroed. Such assumption is not true, as a few H/W NICs can set such flag when H/W offloading the checksum for an UDP encapsulated traffic, the tun driver can inject GSO packets with UDP encapsulation and the problematic layout can also be created via a veth based setup.
Due to the above, in the problematic scenarios, udp4grocomplete() uses the wrong network offset (inner instead of outer) to compute the outer UDP header pseudo checksum, leading to csum validation errors later on in packet processing.
Address the issue always clearing the encapsulation flag at GRO completion time. Such flag will be set again as needed for encapsulated packets by udpgrocomplete().
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-23254?
CVE-2026-23254 has a medium severity rating due to potential data corruption issues under specific network conditions.
How do I fix CVE-2026-23254?
To fix CVE-2026-23254, update your Linux kernel to the latest patched version provided by your distribution.
What systems are affected by CVE-2026-23254?
CVE-2026-23254 affects various versions of the Linux kernel, particularly those that manage UDP GRO operations.
What are the potential impacts of CVE-2026-23254?
The potential impacts of CVE-2026-23254 include data corruption and packet processing errors in network communications.
Is CVE-2026-23254 publicly known?
Yes, CVE-2026-23254 is publicly documented, and information about its resolution and impacts is available in security advisories.