{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-23409 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-23409 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-23409 and fix it if it is affected.\n\nWhat it is: CVE-2026-23409 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-23409 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-23409/ (Markdown: https://insights.sbomify.com/CVE-2026-23409/index.md)","id":"CVE-2026-23409","markdown":"https://insights.sbomify.com/CVE-2026-23409/index.md","name":"CVE-2026-23409","record":{"aliases":["AZL-82031","BELL-CVE-2026-23409","DEBIAN-CVE-2026-23409","GHSA-53jf-v56h-xgqg","UBUNTU-CVE-2026-23409"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel AppArmor","requires_auth":"low_privilege","summary":"A flaw in AppArmor differential encoding verification allows loops to cause infinite loops, leading to denial of service in the Linux kernel.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-835","name":"Loop with Unreachable Exit Condition"}],"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.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"apparmor: fix differential encoding verification","id":"CVE-2026-23409","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"denial_of_service","year":"2026"},"n_packages":0,"n_references":8,"next":{"headline":"apparmor: fix race on rawdata dereference","id":"CVE-2026-23410"},"packages":[],"prev":{"headline":"apparmor: Fix double free of ns_name in aa_replace_profiles()","id":"CVE-2026-23408"},"products":["Linux"],"published":"2026-04-01","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A flaw in AppArmor differential encoding verification allows loops to cause infinite loops, leading to denial of service in the Linux kernel.","url":"https://insights.sbomify.com/CVE-2026-23409/"}