CVE-2026-52956 libceph: Fix potential out-of-bounds access in __ceph_x_decrypt()
An out-of-bounds access in the Linux kernel's Ceph filesystem allows attackers to cause denial of service or potentially execute code via crafted messages.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52956?
CVE-2026-52956 is a high-severity memory corruption vulnerability in Linux kernel, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
libceph: Fix potential out-of-bounds access in __ceph_x_decrypt()
In __ceph_x_decrypt(), a part of the buffer p is interpreted as a ceph_x_encrypt_header, and the magic field of this struct is accessed. This happens without any guarantee that the buffer is large enough to hold this struct. The function parameter ciphertext_len represents the length of the ciphertext to decrypt and is guaranteed to be at most the remaining size of the allocated buffer p. However, this value is not necessarily greater than sizeof(ceph_x_encrypt_header). E.g., a message frame of type FRAME_TAG_AUTH_REPLY_MORE, that is just as long to hold the ciphertext at its end with a ciphertext_len of 8 or less, can trigger an out-of-bounds memory access when accessing hdr->magic.
This patch fixes the issue by adding a check to ensure that the decrypted plaintext in the buffer is large enough to represent at least the ceph_x_encrypt_header.
Weakness: CWE-125
Which versions are affected by CVE-2026-52956?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-52956?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-52956 being exploited?
There is no known exploitation of CVE-2026-52956 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90276, BELL-CVE-2026-52956, DEBIAN-CVE-2026-52956, GHSA-wvxf-4p9h-5vg9, ROOT-OS-DEBIAN-11-CVE-2026-52956, ROOT-OS-DEBIAN-12-CVE-2026-52956 and 4 more.