CVE-2026-23409 | Linux Kernel up to 6.6.129/6.12.76/6.18.17/6.19.7/7.0-rc3 apparmor encoding error

VDB-354625 · CVE-2026-23409 · GCVE-0-2026-23409 LINUX KERNEL UP TO 6.6.129/6.12.76/6.18.17/6.19.7/7.0-RC3 APPARMOR ENCODING ERROR HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 5.3 $0-$5k 1.85+ Summaryinfo A vulnerability was found in Linux Kernel up to 6.6.129/6.12.76/6.18.17/6.19.7/7.0-rc3. It has been classified as critical. The impacted element is an unknown function of the component apparmor. This manipulation causes encoding error. This vulnerability is registered as CVE-2026-23409. No exploit is available. Upgrading the affected component is recommended. Detailsinfo A vulnerability was found in Linux Kernel up to 6.6.129/6.12.76/6.18.17/6.19.7/7.0-rc3. It has been declared as critical. Affected by this vulnerability is an unknown code block of the component apparmor. The manipulation with an unknown input leads to a encoding error vulnerability. The CWE definition for the vulnerability is CWE-172. The product does not properly encode or decode the data, resulting in unexpected values. The impact remains unknown. The summary by CVE is: 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. The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-23409 since 01/13/2026. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/01/2026). Upgrading to version 6.6.130, 6.12.77, 6.18.18, 6.19.8 or 7.0-rc4 eliminates this vulnerability. Applying the patch f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4a/34fc60b125ed1d4eb002c76b0664bf0619492167/623a9d211bbbb031bb1cbdb38b23487648167f8a/1ff4857fac56ac5a90ee63b24db05fa5e91a45aa/39440b137546a3aa383cfdabc605fb73811b6093 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version. Productinfo Type Operating System Vendor Linux Name Kernel Version 6.6.129 6.12.0 6.12.1 6.12.2 6.12.3 6.12.4 6.12.5 6.12.6 6.12.7 6.12.8 6.12.9 6.12.10 6.12.11 6.12.12 6.12.13 6.12.14 6.12.15 6.12.16 6.12.17 6.12.18 6.12.19 6.12.20 6.12.21 6.12.22 6.12.23 6.12.24 6.12.25 6.12.26 6.12.27 6.12.28 6.12.29 6.12.30 6.12.31 6.12.32 6.12.33 6.12.34 6.12.35 6.12.36 6.12.37 6.12.38 6.12.39 6.12.40 6.12.41 6.12.42 6.12.43 6.12.44 6.12.45 6.12.46 6.12.47 6.12.48 6.12.49 6.12.50 6.12.51 6.12.52 6.12.53 6.12.54 6.12.55 6.12.56 6.12.57 6.12.58 6.12.59 6.12.60 6.12.61 6.12.62 6.12.63 6.12.64 6.12.65 6.12.66 6.12.67 6.12.68 6.12.69 6.12.70 6.12.71 6.12.72 6.12.73 6.12.74 6.12.75 6.12.76 6.18.0 6.18.1 6.18.2 6.18.3 6.18.4 6.18.5 6.18.6 6.18.7 6.18.8 6.18.9 6.18.10 6.18.11 6.18.12 6.18.13 6.18.14 6.18.15 6.18.16 6.18.17 6.19.0 6.19.1 6.19.2 6.19.3 6.19.4 6.19.5 6.19.6 6.19.7 7.0-rc1 7.0-rc2 7.0-rc3 License open-source Website Vendor: https://www.kernel.org/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 5.5 VulDB Meta Temp Score: 5.3 VulDB Base Score: 5.5 VulDB Temp Score: 5.3 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Encoding error CWE: CWE-172 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Partially Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: Kernel 6.6.130/6.12.77/6.18.18/6.19.8/7.0-rc4 Patch: f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4a/34fc60b125ed1d4eb002c76b0664bf0619492167/623a9d211bbbb031bb1cbdb38b23487648167f8a/1ff4857fac56ac5a90ee63b24db05fa5e91a45aa/39440b137546a3aa383cfdabc605fb73811b6093 Timelineinfo 01/13/2026 CVE reserved 04/01/2026 +77 days Advisory disclosed 04/01/2026 +0 days VulDB entry created 04/01/2026 +0 days VulDB entry last update Sourcesinfo Vendor: kernel.org Advisory: git.kernel.org Status: Confirmed CVE: CVE-2026-23409 (🔒) GCVE (CVE): GCVE-0-2026-23409 GCVE (VulDB): GCVE-100-354625 Entryinfo Created: 04/01/2026 11:26 Changes: 04/01/2026 11:26 (58) Complete: 🔍 Cache ID: 99:EB0:101 Discussion No comments yet. 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