Skip to content
Fencer Vulns
medium 5.5

CVE-2023-53618 json

btrfs: reject invalid reloc tree root keys with stack dump

published 2025-10-07 13 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-32020

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

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

btrfs: reject invalid reloc tree root keys with stack dump

[BUG] Syzbot reported a crash that an ASSERT() got triggered inside prepare_to_merge().

That ASSERT() makes sure the reloc tree is properly pointed back by its subvolume tree.

[CAUSE] After more debugging output, it turns out we had an invalid reloc tree:

BTRFS error (device loop1): reloc tree mismatch, root 8 has no reloc root, expect reloc root key (-8, 132, 8) gen 17

Note the above root key is (TREE_RELOC_OBJECTID, ROOT_ITEM, QUOTA_TREE_OBJECTID), meaning it's a reloc tree for quota tree.

But reloc trees can only exist for subvolumes, as for non-subvolume trees, we just COW the involved tree block, no need to create a reloc tree since those tree blocks won't be shared with other trees.

Only subvolumes tree can share tree blocks with other trees (thus they have BTRFS_ROOT_SHAREABLE flag).

Thus this new debug output proves my previous assumption that corrupted on-disk data can trigger that ASSERT().

[FIX] Besides the dedicated fix and the graceful exit, also let tree-checker to check such root keys, to make sure reloc trees can only exist for subvolumes.

Patch / fix

  • Linux Linux 5.3, 5.4, 5.15.127, 6.1.46, 6.4.11, 6.5
  • linux Debian 12 6.1.52-1
  • linux Debian 14, Debian 13 6.4.11-1

debian advisories DEBIAN-CVE-2023-53618

  • linux Ubuntu 22.04 LTS 5.15.0-91.101
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1051.56
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1048.56
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1048.53
  • linux-ibm Ubuntu 22.04 LTS 5.15.0-1044.47
  • linux-kvm Ubuntu 22.04 LTS 5.15.0-1048.53
  • linux-azure Ubuntu 22.04 LTS 5.15.0-1053.61
  • linux-gkeop Ubuntu 22.04 LTS 5.15.0-1034.40

ubuntu advisories UBUNTU-CVE-2023-53618

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 Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-rt_debug Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-source-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
  • kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.22.1
  • kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.22.1

suse advisories SUSE-SU-2025:4301-1SUSE-SU-2025:21052-1SUSE-SU-2025:21064-1SUSE-SU-2025:4141-1SUSE-SU-2025:4140-1SUSE-SU-2025:4132-1

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-2023-53618 updated cvss 5.5

kernel: btrfs: reject invalid reloc tree root keys with stack dump

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “To mitigate this issue, prevent module btrfs from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: workaround, no fix available “To mitigate this issue, prevent module btrfs from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.”
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    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

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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.