CVE-2023-34319: Linux: buffer overrun in netback due to unusual packet

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-09-22 · updated 2026-10-15
Weakness: CWE-787

Description

The fix for XSA-423 added logic to Linux'es netback driver to deal with a frontend splitting a packet in a way such that not all of the headers would come in one piece. Unfortunately the logic introduced there didn't account for the extreme case of the entire packet being split into as many pieces as permitted by the protocol, yet still being smaller than the area that's specially dealt with to keep all (possible) headers together. Such an unusual packet would therefore trigger a buffer overrun in the driver.

Affected products

Debian Linux: 10.0
Linux kernel: from 4.9.336 before 4.10; from 4.14.302 before 4.14.321; from 4.19.269 before 4.19.290; from 5.4.227 before 5.4.252; from 5.10.159 before 5.10.189; from 5.15.83 before 5.15.125 — fixed in 4.10, 4.14.321, 4.19.290, 5.10.189, 5.15.125, 5.4.252
xen: from 3.2.0

How to fix

Upgrade to a fixed version: Linux kernel 4.10, 4.14.321, 4.19.290, 5.10.189. Check the vendor advisory for mitigations.

References

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