# CVE-2026-67291: FreeRDP before 3.29.0 Heap Out-of-Bounds Read via GLYPH_FRAGMENT_ADD

> A malicious RDP server can trigger a heap out-of-bounds read in FreeRDP clients, causing a crash via crafted glyph fragment updates.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Aug 2026
- **Updated:** 3 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-67291, GHSA-hgj8-g595-wfc6, GHSA-qx25-fqx8-cgm7, UBUNTU-CVE-2026-67291

## What is CVE-2026-67291?

CVE-2026-67291 is a high-severity memory corruption vulnerability in Freerdp Freerdp, published on 1 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

FreeRDP before 3.29.0 (affected versions <= 3.28.0) contains a heap out-of-bounds read in update_process_glyph_fragments()/glyph_cache_fragment_put() in libfreerdp/cache/glyph.c. When handling a GLYPH_FRAGMENT_ADD update, the code reads a one-byte server-controlled declared fragment size but does not verify it fits within the remaining received buffer before allocating and copying that many bytes. A malicious RDP server can send a short fragment with an oversized declared size, causing the client to read beyond the allocated buffer, resulting in an out-of-bounds read and client crash.

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

## Which versions are affected by CVE-2026-67291?

It affects 1 product.


Products: Freerdp Freerdp.

## How do I fix CVE-2026-67291?

Upgrade to a fixed version.

## Is CVE-2026-67291 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67291 exists.

## Other vulnerabilities in Freerdp Freerdp

- [CVE-2021-37594](https://insights.sbomify.com/CVE-2021-37594/): Other in n/a (critical 9.8)
- [CVE-2021-37595](https://insights.sbomify.com/CVE-2021-37595/): Other in n/a (critical 9.8)
- [CVE-2026-67305](https://insights.sbomify.com/CVE-2026-67305/): FreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr (critical 9.4)
- [CVE-2026-66402](https://insights.sbomify.com/CVE-2026-66402/): FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass (critical 9.3)
- [CVE-2026-67289](https://insights.sbomify.com/CVE-2026-67289/): FreeRDP before 3.29.0 HTTP Proxy Request Injection via Redirection (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-67291 and fix it if it is affected.

What it is: CVE-2026-67291 is a high-severity memory corruption vulnerability in Freerdp Freerdp, published on 1 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67291 exists.

Affected product: Freerdp Freerdp. 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-2026-67291/ (Markdown: https://insights.sbomify.com/CVE-2026-67291/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-67291
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-67291
- OSV: https://osv.dev/vulnerability/CVE-2026-67291

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-67291/
Summaries are generated and may contain mistakes; the official description above is the record.