---
id: CVE-2026-111133
title: >-
  libfsapfs through 20260921 contains an integer underflow in
  libfsapfs_key_encrypted_key_read_data() that allows attackers to trigger heap
  out-of-bounds reads via crafted KEK attributes
summary: >-
  libfsapfs through 20260921 contains an integer underflow in
  libfsapfs_key_encrypted_key_read_data() that allows attackers to trigger heap
  out-of-bounds reads via crafted KEK attributes. Attackers can supply a crafted
  encrypted APFS image…
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H'
cwe:
  - CWE-125
vendor: libyal
product: libfsapfs
affected:
  - libfsapfs <= 20260921
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T19:17:26.957'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-111133'
references:
  - url: 'https://github.com/libyal/libfsapfs'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/libyal/libfsapfs/blob/4c7c1c21f3cfc7d35f0b34b8a47f1f1562d27bbb/libfsapfs/libfsapfs_key_encrypted_key.c#L321-L333
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/libyal/libfsapfs/blob/4c7c1c21f3cfc7d35f0b34b8a47f1f1562d27bbb/libfsapfs/libfsapfs_key_encrypted_key.c#L528-L540
    label: disclosure@vulncheck.com
  - url: >-
      https://hackmd.io/@haind-pwn/libfsapfs-key-encrypted-key-attribute-oob-read
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/libfsapfs-through-20260921-heap-out-of-bounds-read-via-libfsapfs-key-encrypted-key-read-data
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
  - exploit-available
ingestedAt: '2026-10-15T19:25:46.409Z'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-15T19:44:48.953662Z'
---

## Overview

libfsapfs through 20260921 contains an integer underflow in libfsapfs_key_encrypted_key_read_data() that allows attackers to trigger heap out-of-bounds reads via crafted KEK attributes. Attackers can supply a crafted encrypted APFS image with malformed HMAC or wrapped KEK attribute lengths to crash fsapfsinfo, pyfsapfs, dfVFS or plaso and read adjacent heap memory before password checks.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.