Look up another CVE · open CVE-2026-68433 in the interactive tracker
CVE-2026-68433
libceph: bound get_version reply decode to front len
Published 2026-08-12 (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-2026-68433 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
handle_get_version_reply() uses msg->front_alloc_len as the decode boundary for MON_GET_VERSION_REPLY. That is the size of the reused reply buffer, not the number of bytes actually received. A truncated reply can therefore pass ceph_decode_need() and decode the second u64 from stale tail bytes left in the buffer by an earlier message, causing an uninitialized memory read. Use msg->front.iov_len as the receive-side decode boundary, matching other libceph reply handlers and limiting decoding to the bytes that were actually read from the wire.
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/mon_client.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
- 2026-08-12 (2 months ago)source
- CVSS
- 8.6 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.29%, higher than 20.2% 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 |
|---|---|---|
| 3.16 | 5.10.265 | 1307028f0827 |
| 3.16 | 5.15.216 | f6cbf6878f3a |
| 3.16 | 6.1.183 | 72a35070fcef |
| 3.16 | 6.6.148 | 340e0386aa39 |
| 3.16 | 6.12.101 | d60de8253c85 |
| 3.16 | 6.18.42 | 4e7ebfaa0d14 |
| 3.16 | 7.1.6 | 0d934c934ec7 |
| 3.16 | 7.2 | d3c32939fa0e |
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:NAttack vector, network
- The malformed MON_GET_VERSION_REPLY arrives over the ceph messenger TCP connection to a monitor; a malicious/compromised ceph-mon or an on-path attacker on the msgr1/crc-mode session triggers the bug purely with received network data.
- AC:LAttack complexity, low
- The attacker fully controls the reply's hdr.front_len and tid, so truncating the reply to 8 bytes reliably makes the handler decode past the received data every time; no race or memory-layout condition outside attacker control is involved.
- PR:NPrivileges required, none
- The vulnerable decode runs on any reply the client accepts for an outstanding generic request; the attacker acts as the remote server/peer and needs no credentials or account on the victim kernel client.
- UI:NUser interaction, none
- An already-mounted CephFS/RBD client issues mon_get_version requests automatically (osdmap checks, pool-dne checks, remount/latest-map waits), so no local user action is needed once the client is connected.
- S:UScope, unchanged
- The uninitialized read and the resulting bogus epoch stay within the kernel's own libceph client state; no security authority other than the affected kernel is impacted.
- C:LConfidentiality impact, low
- Eight bytes of uninitialized kvmalloc'd heap (or stale bytes of a prior reply) are consumed as req->u.newest; the read stays inside the 32-byte allocation and is not copied to userspace, so it is a small bounded uninitialized-memory disclosure that only leaks indirectly through client behaviour.
- I:LIntegrity impact, low
- The attacker causes kernel state (req->u.newest, r_map_dne_bound, linger map_dne_bound) to be populated from uninitialized memory rather than the wire, corrupting osdmap-epoch bookkeeping and leading to wrong pool-does-not-exist decisions, but gives no arbitrary write.
- A:HAvailability impact, high
- A zero stale value trips WARN_ON(greq->result || !greq->u.newest) in map_check_cb()/linger_map_check_cb() (panic with panic_on_warn), while a huge garbage epoch makes ceph_monc_wait_osdmap() block until mount_timeout or indefinitely and makes check_pool_dne() abort in-flight requests with -ENOENT; all repeatable at will.