5.5

CVE-2026-23409: linux Infinite Loop

CVSS: 5.5v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-23409DEBIAN-CVE-2026-23409
Published 01-04-2026Last modified 11-05-2026
Open JSON

Vulnerability summary

CVE-2026-23409 is a medium (CVSS 5.5) Infinite Loop vulnerability in linux. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 6.8% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.18%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 13 · Related 13
SUSE-SU-2026:21834-1SUSE-SU-2026:2195-1SUSE-SU-2026:2238-1USN-8098-10USN-8152-1USN-8163-1

Timeline

  1. 01-04-2026
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

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 metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

0.00 pp

From 0.18% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.18%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu152 products
  • linux< 5.4.0-227.247 | < 5.15.0-173.183 | < 6.8.0-106.106 | < 6.17.0-19.19
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 5.4.0-1156.166 | < 5.15.0-1103.110 | < 6.8.0-1050.53 | < 6.17.0-1009.9
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < ff7c73744fafe944ed9a7b2b7cf6c8d5557a3d84 | ≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < 1439150cd3c411228b387ab5efca92199d2a659a | ≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < 0fab44285445e9012674396d5c1236a67da518e0 | ≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4a | ≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < 34fc60b125ed1d4eb002c76b0664bf0619492167 | ≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < 623a9d211bbbb031bb1cbdb38b23487648167f8a | ≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < 1ff4857fac56ac5a90ee63b24db05fa5e91a45aa | ≥ 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3, < 39440b137546a3aa383cfdabc605fb73811b6093 | 4.17
  • linux_kernel≥ 4.17.1, < 5.10.253 | ≥ 5.11, < 5.15.203 | ≥ 5.16, < 6.1.169 | ≥ 6.2, < 6.6.130 | ≥ 6.7, < 6.12.77 | ≥ 6.13, < 6.18.18 | ≥ 6.19, < 6.19.8 | 4.17 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6 | 7.0:rc7
Debian1 product
  • linux< 6.1.164-1 | < 6.12.74-2 | < 6.19.6-2

3 vendors · 155 products

References

26 links
Show all 26 references