CVE-2026-23409

MEDIUM EPSS 7.4%
Published Apr 1, 20263mo ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Apr 1, 2026 3mo ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: apparmor: fix differential encoding verification Differential encoding allows loops to be created if it is abused. To prevent this the unpack should verify that a diff-encode chain terminates. Unfortunately the differential encode verification had two bugs. 1. it conflated states that had gone through check and already been marked, with states that were currently being checked and marked. This means that loops in the current chain being verified are treated as a chain that has already been verified. 2. the order bailout on already checked states compared current chain check iterators j,k instead of using the outer loop iterator i. Meaning a step backwards in states in the current chain verification was being mistaken for moving to an already verified state. Move to a double mark scheme where already verified states get a different mark, than the current chain being kept. This enables us to also drop the backwards verification check that was the cause of the second error as any already verified state is already marked.

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
7.4% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-835

Affected Products 15

VendorProductVersionRange
linuxlinux_kernel*≥4.17.1  –  <5.10.253
linuxlinux_kernel*≥5.11  –  <5.15.203
linuxlinux_kernel*≥5.16  –  <6.1.169
linuxlinux_kernel*≥6.2  –  <6.6.130
linuxlinux_kernel*≥6.7  –  <6.12.77
linuxlinux_kernel*≥6.13  –  <6.18.18
linuxlinux_kernel*≥6.19  –  <6.19.8
linuxlinux_kernel4.17any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any

References 8

  • git.kernel.org https://git.kernel.org/stable/c/0fab44285445e9012674396d5c1236a67da518e0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1439150cd3c411228b387ab5efca92199d2a659a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1ff4857fac56ac5a90ee63b24db05fa5e91a45aa
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/34fc60b125ed1d4eb002c76b0664bf0619492167
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/39440b137546a3aa383cfdabc605fb73811b6093
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/623a9d211bbbb031bb1cbdb38b23487648167f8a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ff7c73744fafe944ed9a7b2b7cf6c8d5557a3d84
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/0fab44285445e9012674396d5c1236a67da518e0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1439150cd3c411228b387ab5efca92199d2a659a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1ff4857fac56ac5a90ee63b24db05fa5e91a45aa
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/34fc60b125ed1d4eb002c76b0664bf0619492167
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/39440b137546a3aa383cfdabc605fb73811b6093
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/623a9d211bbbb031bb1cbdb38b23487648167f8a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ff7c73744fafe944ed9a7b2b7cf6c8d5557a3d84
    Patch