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CVE-2026-23409— apparmor: fix differential encoding verification

EPSS 0.01% · P3
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I. Basic Information for CVE-2026-23409

Vulnerability Information
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Vulnerability Title
apparmor: fix differential encoding verification
Source: NVD (National Vulnerability Database)
Vulnerability 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.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于差分编码验证存在缺陷，可能导致循环创建。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
LinuxLinux 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 ~ ff7c73744fafe944ed9a7b2b7cf6c8d5557a3d84 -
LinuxLinux 4.17 -

II. Public POCs for CVE-2026-23409

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III. Intelligence Information for CVE-2026-23409

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Same Patch Batch · Linux · 2026-04-01 · 11 CVEs total

CVE-2026-234117.8 HIGHapparmor: fix race between freeing data and fs accessing it
CVE-2026-234107.8 HIGHapparmor: fix race on rawdata dereference
CVE-2026-234087.8 HIGHapparmor: Fix double free of ns_name in aa_replace_profiles()
CVE-2026-234077.8 HIGHapparmor: fix missing bounds check on DEFAULT table in verify_dfa()
CVE-2026-234067.8 HIGHapparmor: fix side-effect bug in match_char() macro usage
CVE-2026-23405apparmor: fix: limit the number of levels of policy namespaces
CVE-2026-23404apparmor: replace recursive profile removal with iterative approach
CVE-2026-23403apparmor: fix memory leak in verify_header
CVE-2026-23402KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE
CVE-2026-23401KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23409

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