CVE-2025-40100: Linux kernel · btrfs: do not assert we found block group item when creating free space tree
Source GCVE Database
Not known to be exploited.
Data as of 29 Oct 2026, 23:09 UTC
Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Exploitation evidence
Disclosed: evidence found.
CVE published 30 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
AI-suggested
A fix for this issue has been implemented by removing the incorrect assertion in the kernel code. Users should update to a Linux kernel version that includes this fix once it is released. Until then, no specific workaround is described.
Description
CVE-2025-40100 is a vulnerability in the Linux kernel's Btrfs filesystem code related to an incorrect assertion during free space tree creation. The issue arises when a new block group is created in the current transaction but its block group item has not yet been added to the extent tree, causing an assertion failure and kernel crash. This was reported by Syzbot and results in a kernel BUG and system crash.
References
- nvd.nist.gov/vuln/detail/CVE-2025-40100 (opens in a new tab)
- git.kernel.org/stable/c/289498da343b05c886f19b4269429606f86dd17b (opens in a new tab)
- git.kernel.org/stable/c/3fdcfd91b93f930d87843156c7c8cc5fbcf9b144 (opens in a new tab)
- git.kernel.org/stable/c/4f4b9ca73f84130d9fbb0fc02306ce94ce8bdbe6 (opens in a new tab)
- git.kernel.org/stable/c/a5a51bf4e9b7354ce7cd697e610d72c1b33fd949 (opens in a new tab)
- git.kernel.org/stable/c/eb145463f22d7d32d426b29fe9810de9e792b6ba (opens in a new tab)