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CVE-2026-68153
libceph: remove debugfs files before client teardown
Published 2026-08-10 (2 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-2026-68153 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.101-1 | Update the kernel and reboot. Fixed in 6.12.101-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ceph_destroy_client() tears down the monitor client before removing the per-client debugfs files. A concurrent read of the monmap debugfs file can enter monmap_show() after ceph_monc_stop() has freed monc->monmap, triggering a use-after-free. Remove the debugfs files before stopping the OSD and monitor clients. debugfs_remove() drains active handlers and prevents new accesses, so the debugfs callbacks can no longer race the rest of client teardown.
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/ceph_common.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, sid, bookworm · linux-6.12m
- 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
- 2026-08-10 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.0% 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 |
|---|---|---|
| 2.6.34 | 5.10.265 | ac78549d1860 |
| 2.6.34 | 5.15.216 | 463a264e9094 |
| 2.6.34 | 6.1.183 | fe46b7e06f14 |
| 2.6.34 | 6.6.148 | fc1010e7e020 |
| 2.6.34 | 6.12.101 | d3dc8889d39a |
| 2.6.34 | 6.18.42 | 8f5a3abc54ba |
| 2.6.34 | 7.1.6 | b9fedda2f628 |
| 2.6.34 | 7.2 | e4c804726c4a |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | 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:LAttack vector, local
- Exploitation requires local access to debugfs via read() on /sys/kernel/debug/ceph/client*/monmap concurrent with local ceph client teardown via umount or rbd unmap; the bug is not reachable through Ceph network protocol handlers.
- AC:LAttack complexity, low
- The attacker controls both sides of the race by concurrently reading the monmap debugfs file while triggering ceph_destroy_client() via umount/rbd teardown, and can retry until the window between ceph_monc_stop() and debugfs removal is hit.
- PR:LPrivileges required, low
- An unprivileged local user can use user-namespace capabilities (CAP_DAC_READ_SEARCH) to read root-owned debugfs files and race reads against libceph client teardown during automated volume detach or service restarts on Ceph storage nodes.
- UI:NUser interaction, none
- No victim user interaction is required; a local attacker can independently issue debugfs reads and trigger or time against client teardown without requiring another user to click, open files, or mount filesystems.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap memory within the same kernel security domain and does not cross VM, container, or IOMMU boundaries; impact is standard kernel privilege escalation or crash.
- C:HConfidentiality impact, high
- The use-after-free on monc->monmap permits reading freed heap memory containing monitor addresses and entity metadata, and UAF primitives are routinely leveraged for arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- Heap use-after-free on the variable-length ceph_monmap structure enables memory corruption that can be groomed into arbitrary kernel write primitives and local privilege escalation via control-flow hijacking.
- A:HAvailability impact, high
- Concurrent access to freed monmap memory during debugfs iteration can cause kernel oops, BUG, or panic, and UAF corruption reliably threatens system availability even when full exploitation is not attempted.