{"cve":"CVE-2026-23409","nvd":{"published":"2026-04-01T09:16:16.913","modified":"2026-06-17T10:21:31.613","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix differential encoding verification\n\nDifferential encoding allows loops to be created if it is abused. To\nprevent this the unpack should verify that a diff-encode chain\nterminates.\n\nUnfortunately the differential encode verification had two bugs.\n\n1. it conflated states that had gone through check and already been\n   marked, with states that were currently being checked and marked.\n   This means that loops in the current chain being verified are treated\n   as a chain that has already been verified.\n\n2. the order bailout on already checked states compared current chain\n   check iterators j,k instead of using the outer loop iterator i.\n   Meaning a step backwards in states in the current chain verification\n   was being mistaken for moving to an already verified state.\n\nMove to a double mark scheme where already verified states get a\ndifferent mark, than the current chain being kept. This enables us\nto also drop the backwards verification check that was the cause of\nthe second error as any already verified state is already marked.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-835"],"references":["https://git.kernel.org/stable/c/0fab44285445e9012674396d5c1236a67da518e0","https://git.kernel.org/stable/c/1439150cd3c411228b387ab5efca92199d2a659a","https://git.kernel.org/stable/c/1ff4857fac56ac5a90ee63b24db05fa5e91a45aa","https://git.kernel.org/stable/c/34fc60b125ed1d4eb002c76b0664bf0619492167","https://git.kernel.org/stable/c/39440b137546a3aa383cfdabc605fb73811b6093"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:28:18.033120106+00:00"},"epss":{"cve":"CVE-2026-23409","score":0.00184,"percentile":0.07973,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}