CVE-2026-89761
UnknownSummary
A fix has been applied in the Linux kernel for an out-of-bounds write in the AppArmor aa_vec_unique() function. When all label components are distinct, the NULL terminator is written to vec[n], but vec_setup() does not reserve space for this extra entry, causing a write one element past the end of the local array or allocation. The vulnerability can be triggered by an unprivileged task writing to /proc/self/attr/apparmor/current or via lsm_set_self_attr(2), and also through the securityfs .access file which is mode 0666.
Risk Assessment
The flaw can lead to kernel memory corruption, potentially causing a system crash or local privilege escalation. It requires loaded AppArmor policy but no change_profile permission, as the name is parsed before the permission check.
Recommendation
Update the Linux kernel to a version containing the fix that reserves space for the terminator in vec_setup() and DEFINE_VEC(). If immediate patching is not possible, consider restricting access to the securityfs .access file and monitoring for unusual writes to AppArmor attributes.
Other vulnerabilities in Linux kernel AppArmor
See all- CVE-2026-89762Unknown
A use-after-free (UAF) vulnerability in the Linux kernel's AppArmor module, related to begin_current_label_crit_section(), has been fixed. The function could directly replace credential pointers (struct cred) during an LSM hook invocation, causing task->cred and task->real_cred to become inconsistent and leading to freed credential memory still being referenced by other tasks.
- CVE-2026-45966Medium
A vulnerability has been identified in the Linux kernel within AppArmor, leading to a NULL pointer dereference in the __unix_needs_revalidation function. This issue occurs when receiving file descriptors via SCM_RIGHTS, where both the socket and sk pointers may be NULL.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix out-of-bounds write when null terminating a label vec aa_vec_unique() null terminates at vec[n - dups] when VEC_FLAG_TERMINATE is passed. If the components are all distinct no duplicates are dropped, dups is 0 and the terminator goes to vec[n], so the caller has to provide room for n + 1 entries. aa_label_strn_parse() sets up its vector with vec_setup(profile, vec, len, gfp) and then calls aa_vec_unique(vec, len, VEC_FLAG_TERMINATE), but vec_setup() does not reserve the terminator entry. Up to LOCAL_VEC_ENTRIES it uses the local array of LOCAL_VEC_ENTRIES pointers, above that it allocates exactly len pointers. The terminator therefore lands one entry past the end of the local array when len is LOCAL_VEC_ENTRIES, and one entry past the end of the allocation when len is larger. len comes from the number of "//&" separated components in the label name and label_count_strn_entries() does not bound it. An unprivileged task reaches the parse by writing to /proc/self/attr/apparmor/current or through lsm_set_self_attr(2), both of which go through do_setattr(), and the name is parsed before the change_profile permission is checked. The query_label() path behind the securityfs .access file, which is mode 0666, performs no permission check at all. Every component has to resolve to a loaded profile, so a system with policy loaded is required. The other two VEC_FLAG_TERMINATE users work on a label vec that aa_label_alloc() has already sized with "+ 1 for null terminator entry on vec". Reserve the same entry in vec_setup() and DEFINE_VEC(). Passing len + 1 from the caller instead would move len == LOCAL_VEC_ENTRIES out of the local array and into kzalloc().