# CVE-2026-54240: libde265: Pixel accessor signed integer overflow causes heap OOB read/write

> A crafted HEVC stream triggers an integer overflow in libde265, leading to heap out-of-bounds reads or writes that can cause crashes or code execution.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** ALPINE-CVE-2026-54240, BELL-CVE-2026-54240, DEBIAN-CVE-2026-54240, ECHO-48af-523d-62b5, GHSA-ccfw-29x7-rrx3, MINI-wrq7-4x2v-7g7h, ROOT-OS-DEBIAN-11-CVE-2026-54240, UBUNTU-CVE-2026-54240

## What is CVE-2026-54240?

CVE-2026-54240 is a high-severity vulnerability in strukturag libde265, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libde265 is an open source implementation of the h.265 video codec. Versions prior to 1.1.1 use signed 32-bit arithmetic to calculate pixel offsets, allowing a crafted HEVC stream with large image dimensions to trigger an integer overflow and cause out-of-bounds heap reads or writes, potentially disclosing data, corrupting memory, or crashing the decoder. Version 1.1.1 contains a patch.

Weakness: CWE-787 (Out-of-bounds Write), CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-54240?


## How do I fix CVE-2026-54240?

Upgrade to a fixed version.

## Is CVE-2026-54240 being exploited?

There is no known exploitation of CVE-2026-54240 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54240 and fix it if it is affected.

What it is: CVE-2026-54240 is a high-severity vulnerability in strukturag libde265, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54240 in the wild and no public exploit code.

Affected product: strukturag libde265. 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-2026-54240/ (Markdown: https://insights.sbomify.com/CVE-2026-54240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54240
- OSV: https://osv.dev/vulnerability/CVE-2026-54240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54240/
Summaries are generated and may contain mistakes; the official description above is the record.