CVE-2025-38503

Kernel crash via incorrect rebuild assertion

Published Aug 16, 2025 · Updated May 23, 2026

Reachable assertion in the Linux kernel's Btrfs free-space-tree rebuild allows local users to crash the kernel during a read-write remount. The populate_free_space_tree function wrongly asserts that btrfs_search_slot_for_read returns zero when an empty, highest-offset block group has no extent-root item, although the block-group-tree lookup correctly returns one. Reachability requires low-privileged local access, the block group tree feature, an empty highest-offset block group, and a free-space-tree rebuild; the resulting BUG interrupts the host.

CVSS severity5.5
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Reachable assertion in the Linux kernel's Btrfs free-space-tree rebuild allows local users to crash the kernel during a read-write remount. The populate_free_space_tree function wrongly asserts that btrfs_search_slot_for_read returns zero when an empty, highest-offset block group has no extent-root item, although the block-group-tree lookup correctly returns one. Reachability requires low-privileged local access, the block group tree feature, an empty highest-offset block group, and a free-space-tree rebuild; the resulting BUG interrupts the host.

The record

CVE
CVE-2025-38503
Published
Aug 16, 2025
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-617, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 16, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1c56ab991903dce60e905a08f431c0e6f79b9b9e <0bcc14f36c7ad37121cf5c0ae18cdde5bfad9c4e
  2. Affected versionversion=1c56ab991903dce60e905a08f431c0e6f79b9b9e <1961d20f6fa8903266ed9bd77c691924c22c8f02
  3. Affected versionversion=1c56ab991903dce60e905a08f431c0e6f79b9b9e <6bbe6530b1db7b4365ce9e86144c18c5d73b2c5b
  4. Affected versionversion=1c56ab991903dce60e905a08f431c0e6f79b9b9e <7c77df23324f60bcff0ea44392e2c82e9486640c
  5. Affected versionversion=1c56ab991903dce60e905a08f431c0e6f79b9b9e <f4428b2d4c68732653e93f748f538bdee639ff80
  6. Affected versionversion=6.0.19 <6.1
  7. Affected versionversion=6.1
  8. Affected versionversion=dc74beca1672adf3874e6cb6c26917139e2faf01

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1c56ab991903dce60e905a08f431c0e6f79b9b9e <0bcc14f36c7ad37121cf5c0ae18cdde5bfad9c4e; version=1c56ab991903dce60e905a08f431c0e6f79b9b9e <1961d20f6fa8903266ed9bd77c691924c22c8f02; version=1c56ab991903dce60e905a08f431c0e6f79b9b9e <6bbe6530b1db7b4365ce9e86144c18c5d73b2c5b; version=1c56ab991903dce60e905a08f431c0e6f79b9b9e <7c77df23324f60bcff0ea44392e2c82e9486640c; version=1c56ab991903dce60e905a08f431c0e6f79b9b9e <f4428b2d4c68732653e93f748f538bdee639ff80; version=6.0.19 <6.1; version=6.1; version=dc74beca1672adf3874e6cb6c26917139e2faf01

Published CVSS scores

6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo