high 7.8

CVE-2026-68442 json

btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

published 2026-08-12 2 mo ago modified 2026-10-19 20 d ago also EUVD-2026-57050

cvss: 7.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits: 0; none known

In the Linux kernel, the following vulnerability has been resolved:

When btrfs_drop_extent_map_range() splits an extent map, the new split maps inherit the original map's flags through a local 'flags' variable. Commit f86f7a75e2fb ("btrfs: use the flags of an extent map to identify the compression type") changed the EXTENT_FLAG_LOGGING clearing to operate on em->flags instead of that local 'flags' copy, so a split of an extent map that is currently being logged wrongly inherits EXTENT_FLAG_LOGGING.

The flag is then never cleared on the split, and when it is freed while still on the inode's modified_extents list (for example by the extent map shrinker) it trips the WARN_ON(!list_empty(&em->list)) in btrfs_free_extent_map() and leads to a use-after-free.

Clear EXTENT_FLAG_LOGGING from the local 'flags' copy used for the splits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the behaviour prior to f86f7a75e2fb.

Patch / fix

fixed in 1 distros 4 links 4

Linux Linux 6.12.101, 6.18.42, 7.1.6, 7.2

debian ubuntu suse opensuse

linux Debian 13 6.12.101-1
linux Debian 14 7.1.6-1
linux-6.12 Debian 12 6.12.101-1~deb12u1

debian advisories DEBIAN-CVE-2026-68442

linux Ubuntu 24.04 LTS 6.8.0-147.147
linux Ubuntu 26.04 LTS 7.0.0-38.38
linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
linux-aws Ubuntu 26.04 LTS 7.0.0-1014.14
linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79
linux-gcp Ubuntu 26.04 LTS 7.0.0-1014.14
linux-gke Ubuntu 24.04 LTS 6.8.0-1066.74
linux-gke Ubuntu 26.04 LTS 7.0.0-1008.9

ubuntu advisories UBUNTU-CVE-2026-68442

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-rt Linux Micro 6.2 6.12.0-160000.38.1
kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.38.1
kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1.160000.2.23
kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
kernel-azure SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.38.1
kernel-obs-qa SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.38.1

suse advisories SUSE-SU-2026:23887-1 SUSE-SU-2026:23902-1 SUSE-SU-2026:23897-1 SUSE-SU-2026:23881-1

kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-68442 updated 2026-11-05 cvss 5.5

kernel: btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

Red Hat Enterprise Linux 10 kernel 6.12.0-257.el10
affected: workaround, no fix available
Red Hat Enterprise Linux for NVIDIA 26 kernel 6.12.0-257.el10
affected: workaround, no fix planned “Out of support scope”
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +2 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +9 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +30 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +84 more Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 23 d ago (2026-10-16)

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-416 Use After Free

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2026-68442
NVD CVE-2026-68442

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary