CVE-2026-43067

CRITICAL EPSS 32.1%
Published May 5, 20261mo ago · Modified Jun 17, 20261w ago
9.8 CVSS 3.1
Critical
Find Similar
Published May 5, 2026 1mo ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().

CVSS Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
32.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Affected Products 6

VendorProductVersionRange
linuxlinux_kernel*≥5.15.203  –  <5.16
linuxlinux_kernel*≥6.6.130  –  <6.6.134
linuxlinux_kernel*≥6.12.77  –  <6.12.80
linuxlinux_kernel*≥6.18.14  –  <6.18.21
linuxlinux_kernel*≥6.19.4  –  <6.19.11
linuxlinux_kernel6.1.167any

References 6

  • git.kernel.org https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930
    Patch