← CVE Intelligence

CVE-2026-89761

apparmor: fix out-of-bounds write when null terminating a label vec PUBLISHED

Description (CNA)

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().

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected f1bd904175e8190ce14aedee37e207ab51fe3b30 before b17c8f5dcb36a032688847b2bce4bd813b4baad1; affected f1bd904175e8190ce14aedee37e207ab51fe3b30 before 9124e078ea2250d8d01d2162a550acb01ef5bf48; affected f1bd904175e8190ce14aedee37e207ab51fe3b30 before 28069434aef66b9d084f0609b7a29c171846815e; affected f1bd904175e8190ce14aedee37e207ab51fe3b30 before 36bdd0b45ec3f4822832a56e9db8674c8450dfce; affected f1bd904175e8190ce14aedee37e207ab51fe3b30 before 9f1e40193eef7f047e6b77cfb4b4cafdecd7a123
Linux / Linuxaffected 4.13; unaffected 0 before 4.13; unaffected 6.6.160 through 6.6.*; unaffected 6.12.109 through 6.12.*; unaffected 6.18.50 through 6.18.*; unaffected 7.2.4 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References