CVE-2026-45912
What it is
In the Linux kernel, the following vulnerability has been resolved: ext4: don't cache extent during splitting extent Caching extents during the splitting process is risky, as it may result in stale extents remaining in the status tree. Moreover, in most cases, the corresponding extent block entries are likely already cached before the split happens, making caching here not particularly useful. Assume we have an unwritten extent, and then DIO writes the first half. [UUUUUUUUUUUUUUUU] on-disk extent U: unwritten extent [UUUUUUUUUUUUUUUU] extent status tree |<- ->| ----> dio write this range First, when ext4_split_extent_at() splits this extent, it truncates the existing extent and then inserts a new one. During this process, this extent status entry may be shrunk, and calls to ext4_find_extent() and ext4_cache_extents() may occur, which could potentially insert the truncated range as a hole into the extent status tree. After the split is completed, this hole is not replaced with the correct status. [UUUUUUU|UUUUUUUU] on-disk extent U: unwritten extent [UUUUUUU|HHHHHHHH] extent status tree H: hole Then, the outer calling functions will not correct this remaining hole extent either. Finally, if we perform a delayed buffer write on this latter part, it will re-insert the delayed extent and cause an error in space accounting. In adition, if the unwritten extent cache is not shrunk during the splitting, ext4_cache_extents() also conflicts with existing extents when caching extents. In the future, we will add checks when caching extents, which will trigger a warning. Therefore, Do not cache extents that are being split.
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.
- Exploit odds
- 0.1% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.1% in the next 30 days (EPSS).
- Severity: 5.5 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.1% · EPSS, next 30 days
- Record status
- Undergoing Analysis
Affected
- Linux Kernel < 5.10.252
- Linux Kernel < 5.15.202
- Linux Kernel < 6.1.165
- Linux Kernel < 6.6.128
- Linux Kernel < 6.12.75
- Linux Kernel < 6.18.14
- Linux Kernel < 6.19.4
Attack profile CVSS 3.1 · 5.5
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-45912.md and follow it. Check whether this project is affected by CVE-2026-45912. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/4c2d9dac4d328244f9365b0a1fa27ec802821820
- https://git.kernel.org/stable/c/5b1f4290453314e11cd8e15c7baa8a9b76c19b23
- https://git.kernel.org/stable/c/692103feca376ae4298c92aa8828015d20f1d87b
- https://git.kernel.org/stable/c/8302b5b4aacdbb378f7b1216bb2ee782b5142415
- https://git.kernel.org/stable/c/8b4b19a2f96348d70bfa306ef7d4a13b0bcbea79
- https://git.kernel.org/stable/c/93b2ebbbcb2e63cfc21a1946dfe91d3aa7952036
- https://git.kernel.org/stable/c/96007fd3c106aea773c1afae2d6f64cceb6da208
- https://git.kernel.org/stable/c/9a2b95cdaf07785e2739199037bd9c0863ccc1be
References
- https://git.kernel.org/stable/c/4c2d9dac4d328244f9365b0a1fa27ec802821820
- https://git.kernel.org/stable/c/5b1f4290453314e11cd8e15c7baa8a9b76c19b23
- https://git.kernel.org/stable/c/692103feca376ae4298c92aa8828015d20f1d87b
- https://git.kernel.org/stable/c/8302b5b4aacdbb378f7b1216bb2ee782b5142415
- https://git.kernel.org/stable/c/8b4b19a2f96348d70bfa306ef7d4a13b0bcbea79
- https://git.kernel.org/stable/c/93b2ebbbcb2e63cfc21a1946dfe91d3aa7952036
- https://git.kernel.org/stable/c/96007fd3c106aea773c1afae2d6f64cceb6da208
- https://git.kernel.org/stable/c/9a2b95cdaf07785e2739199037bd9c0863ccc1be