CVE-2023-46838: Linux: netback processing of zero-length transmit fragment

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-01-29 · updated 2026-06-17
Weakness: CWE-476

Description

Transmit requests in Xen's virtual network protocol can consist of multiple parts. While not really useful, except for the initial part any of them may be of zero length, i.e. carry no data at all. Besides a certain initial portion of the to be transferred data, these parts are directly translated into what Linux calls SKB fragments. Such converted request parts can, when for a particular SKB they are all of length zero, lead to a de-reference of NULL in core networking code.

Affected products

Debian Linux: 10.0
Fedoraproject Fedora: 38, 39
Linux kernel: from 4.14 before 4.19.306; from 4.20 before 5.4.268; from 5.5 before 5.10.209; from 5.11 before 5.15.148; from 5.16 before 6.1.75; from 6.2 before 6.6.14 — fixed in 4.19.306, 5.10.209, 5.15.148, 5.4.268, 6.1.75, 6.6.14

How to fix

Upgrade to a fixed version: Linux kernel 4.19.306, 5.10.209, 5.15.148, 5.4.268. Check the vendor advisory for mitigations.

References

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