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CVE-2026-52958
libceph: Fix potential out-of-bounds access in osdmap_decode()
Published 2026-06-24 (4 months ago) by the Linux kernel CNA. Subsystem net/ceph. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-52958 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
When decoding osd_state and osd_weight from an incoming osdmap in osdmap_decode(), both are decoded for each osd, i.e., map->max_osd times. The ceph_decode_need() check only accounts for sizeof(*map->osd_weight) once. This can potentially result in an out-of-bounds memory access if the incoming message is corrupted such that the max_osd value exceeds the actual content of the osdmap message. This patch fixes the issue by changing the corresponding part in the ceph_decode_need() check to account for map->max_osd*sizeof(*map->osd_weight).
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/ceph/osdmap.c
- What this is
- CEPH COMMON CODE (LIBCEPH)MAINTAINERS section matched on net/ceph/ · ceph-devel@vger.kernel.org · Supported
- Kernel module
- libceph
Check it on the machine
grep -w CONFIG_CEPH_LIB /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w libcephPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_CEPH_LIB
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-06-24 (4 months ago)source
- CVSS
- 9.1 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.73%, higher than 53.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/ceph
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.3 | 5.10.258 | 36a79759a288 |
| 5.3 | 5.15.209 | 3f2575bb7f95 |
| 5.3 | 6.1.175 | 8713bbc4b2b9 |
| 5.3 | 6.6.141 | 0d2dd7e6bb74 |
| 5.3 | 6.12.91 | e7187f33c024 |
| 5.3 | 6.18.33 | 48df98d12b15 |
| 5.3 | 7.0.10 | ee933694645d |
| 5.3 | 7.1 | 35d0ed82d03e |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The vulnerable decoder processes Ceph OSD map messages received over Ceph messenger connections from monitors or OSDs. A malicious or compromised network Ceph peer can deliver the crafted map to a connected kernel client.
- AC:LAttack complexity, low
- The trigger is a deterministic malformed OSD map with `max_osd` larger than the supplied `osd_weight` content. No race or condition outside the attacker's control is required.
- PR:NPrivileges required, none
- The attacker does not need privileges on the vulnerable Linux system; the crafted data is supplied by a remote Ceph peer. Ceph also supports auth-none deployments, so the highest defensible scenario does not require authenticated attacker privileges.
- UI:NUser interaction, none
- Once the kernel Ceph client is connected, OSD map updates are processed asynchronously without a user action. The attacker can trigger parsing by sending the crafted map over the established network connection.
- S:UScope, unchanged
- The impact is within the kernel/client system that parses the malicious Ceph message. This is not a VM escape, IOMMU bypass, or other cross-scope boundary change.
- C:HConfidentiality impact, high
- The bug is an out-of-bounds read from the received message buffer, and the read can extend beyond a small bounded area based on attacker-controlled `max_osd`. Following the higher-severity rule for OOB reads, this supports high confidentiality impact.
- I:NIntegrity impact, none
- The faulty loop reads past the input buffer into the allocated `osd_weight` array but does not write out of bounds or provide a clear kernel memory write primitive. The malformed full map is rejected after decoding fails.
- A:HAvailability impact, high
- The out-of-bounds kernel read can fault or otherwise crash the kernel when it crosses invalid memory, and malformed OSD maps can be sent repeatedly by the network peer. Kernel crash or oops is high availability impact.