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CVE-2026-68158
libceph: Fix multiplication overflow in decode_new_up_state_weight()
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-2026-68158 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
If a message of type CEPH_MSG_OSD_MAP contains a (maliciously) corrupted osdmap, out-of-bounds memory accesses may occur in decode_new_up_state_weight(). This happens because the bounds check for the new_state part is based on calculating its length depending on a len value read from the incoming message. This calculation may overflow leading to an incorrect bounds check. Subsequently, out-of-bounds reads may occur when decoding this part. This patch switches the multiplication to use check_mul_overflow() to abort processing the osdmap if an overflow occurred. Therefore, osdmaps/messages containing large values for len that result in a multiplication overflow are treated as invalid. [ idryomov: rename new_state_len -> new_state_item_size, formatting ]
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, 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
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.71%, higher than 52.8% 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 |
|---|---|---|
| 4.7 | 5.10.265 | 2ceee3b77b83 |
| 4.7 | 5.15.216 | e4473751cc37 |
| 4.7 | 6.1.183 | f6961070c326 |
| 4.7 | 6.6.148 | 05c90e059269 |
| 4.7 | 6.12.101 | 143ba49ead77 |
| 4.7 | 6.18.42 | 1732d89dfcd7 |
| 4.7 | 7.1.6 | bee4b5b53e7b |
| 4.7 | 7.2 | 98917a499ec7 |
| 3.10.103 | 0 | 0 |
| 3.12.63 | 0 | 0 |
| 3.14.75 | 0 | 0 |
| 3.16.39 | 0 | 0 |
| 3.18.39 | 0 | 0 |
| 4.1.30 | 0 | 0 |
| 4.4.17 | 0 | 0 |
| 4.6.6 | 0 | 0 |
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
- Malformed incremental osdmap data is delivered in CEPH_MSG_OSD_MAP over TCP from a Ceph monitor (mon_dispatch) or OSD (osd_dispatch) to libceph clients (CephFS/RBD), and the overflow is triggered while decoding received network bytes in osdmap_apply_incremental().
- AC:LAttack complexity, low
- A compromised or attacker-controlled monitor/OSD can publish an incremental osdmap with epoch N+1 and a crafted new_state length that wraps the multiply, reliably bypassing bounds checks without races or victim-specific memory layout.
- PR:NPrivileges required, none
- Exploitation requires no privileges on the victim host; a malicious cluster peer or on-path attacker that can deliver forged osdmaps to an already-connected kernel Ceph client needs no local account, capabilities, or user-namespace tricks.
- UI:NUser interaction, none
- Once a host is a Ceph client, osdmap subscriptions and updates are applied automatically by the kernel; no additional mount, open, or interactive step is needed at exploit time beyond the existing client session.
- S:UScope, unchanged
- Impact is confined to kernel memory and libceph client state on the Ceph client host (info leak, map corruption, crash, or privilege escalation); it does not cross VM, IOMMU, or sandbox boundaries to another security authority.
- C:HConfidentiality impact, high
- Integer-overflow bypass lets decode_new_up_state_weight() run bare ceph_decode_32/8 loops past the message end, performing out-of-bounds reads of adjacent kernel heap/slack memory that can disclose pointers and other sensitive data.
- I:HIntegrity impact, high
- Misaligned decoding also drives attacker-controlled osd/xorstate/weight values into map->osd_weight[], map->osd_state[], and map->osd_addr[] updates (including memset), corrupting kernel osdmap state in ways usable for further exploitation.
- A:HAvailability impact, high
- Unbounded out-of-bounds reads while parsing osdmaps can fault on unmapped pages and trigger kernel oops/panic; map corruption can also cause persistent client failure, repeatable on each malicious incremental map.