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CVE-2026-89761— apparmor: fix out-of-bounds write when null terminating a label vec

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于apparmor在空终止标签向量时，vec_setup()未为终止符预留条目，导致越界写入，可能造成内存损坏或拒绝服务。

CVSS 7.8 · High EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1548 · Abuse Elevation Control Mechanism

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux f1bd904175e8190ce14aedee37e207ab51fe3b30< 9124e078ea2250d8d01d2162a550acb01ef5bf48 affected
f1bd904175e8190ce14aedee37e207ab51fe3b30< 28069434aef66b9d084f0609b7a29c171846815e affected
f1bd904175e8190ce14aedee37e207ab51fe3b30< 36bdd0b45ec3f4822832a56e9db8674c8450dfce affected
f1bd904175e8190ce14aedee37e207ab51fe3b30< 9f1e40193eef7f047e6b77cfb4b4cafdecd7a123 affected
4.13 affected
< 4.13 unaffected
6.12.109≤ 6.12.* unaffected
6.18.50≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-89761

Vulnerability Information
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Vulnerability Title
apparmor: fix out-of-bounds write when null terminating a label vec
Source: CVE Program / CVE List V5
Vulnerability Description
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().
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于apparmor在空终止标签向量时，vec_setup()未为终止符预留条目，导致越界写入，可能造成内存损坏或拒绝服务。
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

Vendor Product Affected Versions CPE Subscribe
Linux Linux f1bd904175e8190ce14aedee37e207ab51fe3b30 ~ 9124e078ea2250d8d01d2162a550acb01ef5bf48 -
Linux Linux 4.13 -

II. Public POCs for CVE-2026-89761

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III. Intelligence Information for CVE-2026-89761

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Patches & Fixes for CVE-2026-89761 (4)

Same Patch Batch · Linux · 2026-09-11 · 431 CVEs total

CVE-2026-89669 9.8 CRITICAL nfsd: initialize copy-notify stateid before publishing it
CVE-2026-89536 9.8 CRITICAL SUNRPC: wait for in-flight client TLS handshake callback
CVE-2026-89533 9.8 CRITICAL svcrdma: Fix offset arithmetic in read_chunk_range
CVE-2026-81002 9.8 CRITICAL xdp: fix zero-copy frame layout
CVE-2026-89643 9.8 CRITICAL audit: avoid dropping live tree ref on fsnotify rule autoremove
CVE-2026-89526 9.8 CRITICAL svcrdma: Validate Read chunk positions before reconstruction
CVE-2026-89652 9.8 CRITICAL ceph: bound copied dentry name length in NFS export get_name
CVE-2026-89651 9.8 CRITICAL ceph: bound MDSCapAuth path and fs_name decode in handle_session()
CVE-2026-89653 9.8 CRITICAL ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode
CVE-2026-89654 9.8 CRITICAL ceph: fix UAF in check_new_map() on session freed during unlock
CVE-2026-89656 9.8 CRITICAL libceph: reject buckets with mismatched CRUSH ids
CVE-2026-89655 9.8 CRITICAL ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock
CVE-2026-89712 9.8 CRITICAL NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock
CVE-2026-89658 9.8 CRITICAL NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup
CVE-2026-89660 9.8 CRITICAL NFSD: Prevent client use-after-free during admin state revocation
CVE-2026-89659 9.8 CRITICAL NFSD: Prevent client use-after-free during delegation revoke
CVE-2026-89708 9.8 CRITICAL nfsd: RCU-protect cl_cb_session to fix use-after-free on session teardown
CVE-2026-89662 9.8 CRITICAL NFSD: Prevent lock owner use-after-free during client teardown
CVE-2026-89689 9.8 CRITICAL nfsd: don't free session slots that are still in use
CVE-2026-89686 9.8 CRITICAL nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke

Showing top 20 of 431 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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