CVE-2026-43304: libceph: define and enforce CEPH_MAX_KEY_LEN

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-08 · updated 2026-10-19
Weakness: CWE-121

Description

In the Linux kernel, the following vulnerability has been resolved: libceph: define and enforce CEPH_MAX_KEY_LEN When decoding the key, verify that the key material would fit into a fixed-size buffer in process_auth_done() and generally has a sane length. The new CEPH_MAX_KEY_LEN check replaces the existing check for a key with no key material which is a) not universal since CEPH_CRYPTO_NONE has to be excluded and b) doesn't provide much value since a smaller than needed key is just as invalid as no key -- this has to be handled elsewhere anyway.

Affected products

Linux kernel: from 5.11 before 5.15.202; from 5.16 before 6.1.165; from 6.2 before 6.6.128; from 6.7 before 6.12.75; from 6.13 before 6.18.16; from 6.19 before 6.19.6 — fixed in 5.15.202, 6.1.165, 6.12.75, 6.18.16, 6.19.6, 6.6.128

How to fix

Upgrade to a fixed version: Linux kernel 5.15.202, 6.1.165, 6.12.75, 6.18.16. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-43304 or the next vulnerability affects your stack