# CVE-2026-111133: libfsapfs through 20260921 Heap Out-of-Bounds Read via libfsapfs_key_encrypted_key_read_data

> Attackers can trigger heap out-of-bounds reads and crashes in libfsapfs by supplying crafted APFS images with malformed key attributes.

- **Severity:** Medium 6.9 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-111133, GHSA-6q77-mgpq-cm3g, UBUNTU-CVE-2026-111133

## What is CVE-2026-111133?

CVE-2026-111133 is a medium-severity vulnerability in libyal libfsapfs, published on 15 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-111133?


## How do I fix CVE-2026-111133?

No fix has been published for CVE-2026-111133 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-111133 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111133 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-111133 and fix it if it is affected.

What it is: CVE-2026-111133 is a medium-severity vulnerability in libyal libfsapfs, published on 15 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111133 exists.

Affected product: libyal libfsapfs. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-111133/ (Markdown: https://insights.sbomify.com/CVE-2026-111133/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-111133
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111133
- OSV: https://osv.dev/vulnerability/CVE-2026-111133

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-111133/
Summaries are generated and may contain mistakes; the official description above is the record.