# CVE-2026-33165: heap out-of-bounds write in libde265 1.0.16

> A crafted HEVC bitstream triggers a heap out-of-bounds write in libde265, potentially allowing code execution or denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **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:** Yes
- **Published:** 20 Mar 2026
- **Updated:** 24 Mar 2026
- **Also known as:** ALPINE-CVE-2026-33165, DEBIAN-CVE-2026-33165, ECHO-fdba-52af-519e, GHSA-653q-9f73-8hvg, JLSEC-2026-159, UBUNTU-CVE-2026-33165

## What is CVE-2026-33165?

CVE-2026-33165 is a medium-severity memory corruption vulnerability in Struktur Libde265, published on 20 Mar 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

libde265 is an open source implementation of the h.265 video codec. Prior to version 1.0.17, a crafted HEVC bitstream causes an out-of-bounds heap write confirmed by AddressSanitizer. The trigger is a stale ctb_info.log2unitSize after an SPS change where PicWidthInCtbsY and PicHeightInCtbsY stay constant but Log2CtbSizeY changes, causing set_SliceHeaderIndex to index past the allocated image metadata array and write 2 bytes past the end of a heap allocation. This issue has been patched in version 1.0.17.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-33165?

It affects 1 product.


Products: Struktur Libde265.

## How do I fix CVE-2026-33165?

Upgrade to a fixed version.

## Is CVE-2026-33165 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33165 exists.

## Other vulnerabilities in Struktur Libde265

- [CVE-2023-49465](https://insights.sbomify.com/CVE-2023-49465/): Memory corruption in n/a (high 8.8)
- [CVE-2023-49467](https://insights.sbomify.com/CVE-2023-49467/): Memory corruption in n/a (high 8.8)
- [CVE-2023-49468](https://insights.sbomify.com/CVE-2023-49468/): Memory corruption in n/a (high 8.8)
- [CVE-2023-27103](https://insights.sbomify.com/CVE-2023-27103/): Memory corruption in n/a (high 8.8)
- [CVE-2026-33164](https://insights.sbomify.com/CVE-2026-33164/): NULL Pointer Dereference in libde265 (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33165 and fix it if it is affected.

What it is: CVE-2026-33165 is a medium-severity memory corruption vulnerability in Struktur Libde265, published on 20 Mar 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-2026-33165 exists.

Affected product: Struktur 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-2026-33165/ (Markdown: https://insights.sbomify.com/CVE-2026-33165/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33165
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33165
- OSV: https://osv.dev/vulnerability/CVE-2026-33165

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33165/
Summaries are generated and may contain mistakes; the official description above is the record.