# CVE-2026-3949: strukturag libheif HEIF File decoder_vvdec.cc vvdec_push_data2 out-of-bounds

> A local attacker can trigger an out-of-bounds read in libheif's HEIF decoder, potentially causing crashes or leaking memory.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Mar 2026
- **Updated:** 11 Mar 2026
- **Also known as:** DEBIAN-CVE-2026-3949, ECHO-335c-65c6-bca4, GHSA-2rvx-jpm5-g848, SUSE-SU-2026:1660-1, openSUSE-SU-2026:10460-1

## What is CVE-2026-3949?

CVE-2026-3949 is a medium-severity memory corruption vulnerability in strukturag libheif, published on 11 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability was determined in strukturag libheif up to 1.21.2. This affects the function vvdec_push_data2 of the file libheif/plugins/decoder_vvdec.cc of the component HEIF File Parser. Executing a manipulation of the argument size can lead to out-of-bounds read. The attack needs to be launched locally. The exploit has been publicly disclosed and may be utilized. This patch is called b97c8b5f198b27f375127cd597a35f2113544d03. It is advisable to implement a patch to correct this issue.

Weakness: CWE-125 (Out-of-bounds Read), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-3949?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libheif` | openSUSE:Tumbleweed | All versions | 1.21.2-2.1 |

## How do I fix CVE-2026-3949?

Apply the vendor's patch.

## Is CVE-2026-3949 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3949 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3949 and fix it if it is affected.

What it is: CVE-2026-3949 is a medium-severity memory corruption vulnerability in strukturag libheif, published on 11 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3949 exists.

Affected product: strukturag libheif. 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-2026-3949/ (Markdown: https://insights.sbomify.com/CVE-2026-3949/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3949
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3949
- OSV: https://osv.dev/vulnerability/CVE-2026-3949

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3949/
Summaries are generated and may contain mistakes; the official description above is the record.