CVE-2026-23409

Description

In the Linux kernel, the following vulnerability has been resolved:apparmor: fix differential encoding verificationDifferential encoding allows loops to be created if it is abused. Toprevent this the unpack should verify that a diff-encode chainterminates.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 adifferent mark, than the current chain being kept. This enables usto also drop the backwards verification check that was the cause ofthe second error as any already verified state is already marked.

Risk Information

Associated Vulnerability

Patch Details

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234