CVE-2026-46024: libceph: Prevent potential null-ptr-deref in ceph_handle_auth_reply()

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-27 · updated 2026-10-19
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: libceph: Prevent potential null-ptr-deref in ceph_handle_auth_reply() If a message of type CEPH_MSG_AUTH_REPLY contains a zero value for both protocol and result, this is currently not treated as an error. In case of ac->negotiating == true and ac->protocol > 0, this leads to setting ac->protocol = 0 and ac->ops = NULL. Thereafter, the check for ac->protocol != protocol returns false, and init_protocol() is not called. Subsequently, ac->ops->handle_reply() is called, which leads to a null pointer dereference, because ac->ops is still NULL. This patch changes the check for ac->protocol != protocol to !ac->protocol, as this also includes the case when the protocol was set to zero in the message. This causes the message to be treated as containing a bad auth protocol.

Affected products

Linux kernel: from 2.6.34.1 before 5.15.209; from 5.16 before 6.1.175; from 6.2 before 6.6.140; from 6.7 before 6.12.86; from 6.13 before 6.18.27; from 6.19 before 7.0.4 — fixed in 5.15.209, 6.1.175, 6.12.86, 6.18.27, 6.6.140, 7.0.4

How to fix

Upgrade to a fixed version: Linux kernel 5.15.209, 6.1.175, 6.12.86, 6.18.27. Check the vendor advisory for mitigations.

References

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