CVE-2026-52955
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk31th percentile - higher than 31% of all known CVEs
Summary
In the Linux kernel, the crush_decode() function in libceph is vulnerable to an out-of-bounds access when two fields specifying the bucket algorithm in a CRUSH map differ. This can lead to memory corruption and potential exploitation.
Risk Assessment
An attacker can remotely send a crafted OSD map, causing a system crash (denial of service) or potentially gaining access to kernel memory, which may lead to privilege escalation.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit adding bucket algorithm validation). For production systems, apply the security patch after testing.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: libceph: Fix potential out-of-bounds access in crush_decode() A message of type CEPH_MSG_OSD_MAP containing a crush map with at least one bucket has two fields holding the bucket algorithm. If the values in these two fields differ, an out-of-bounds access can occur. This is the case because the first algorithm field (alg) is used to allocate the correct amount of memory for a bucket of this type, while the second algorithm field inside the bucket (b->alg) is used in the subsequent processing. This patch fixes the issue by adding a check that compares alg and b->alg and aborts the processing in case they differ. Furthermore, b->alg is set to 0 in this case, because the destruction of the crush map also uses this field to determine the bucket type, which can again result in an out-of-bounds access when trying to free the memory pointed to by the fields of the bucket. To correctly free the memory allocated for the bucket in such a case, the corresponding call to kfree is moved from the algorithm-specific crush_destroy_bucket functions to the generic crush_destroy_bucket().