# CVE-2019-15691: Use after free in TigerVNC

> A stack use-after-free in TigerVNC's ZRLEDecoder allows remote attackers to execute arbitrary code via network connectivity.

- **Severity:** High 7.2 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Dec 2019
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-15691, GHSA-vmc8-ggh9-8p8j, UBUNTU-CVE-2019-15691

## What is CVE-2019-15691?

CVE-2019-15691 is a high-severity use after free vulnerability in Opensuse Leap, published on 26 Dec 2019. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

TigerVNC version prior to 1.10.1 is vulnerable to stack use-after-return, which occurs due to incorrect usage of stack memory in ZRLEDecoder. If decoding routine would throw an exception, ZRLEDecoder may try to access stack variable, which has been already freed during the process of stack unwinding. Exploitation of this vulnerability could potentially result into remote code execution. This attack appear to be exploitable via network connectivity.

Weakness: CWE-672 (Operation on a Resource after Expiration or Release), CWE-825 (Expired Pointer Dereference)

## Which versions are affected by CVE-2019-15691?

It affects 2 products.


Products: Opensuse Leap, Tigervnc Tigervnc.

## How do I fix CVE-2019-15691?

Upgrade to a fixed version.

## Is CVE-2019-15691 being exploited?

There is no known exploitation of CVE-2019-15691 in the wild and no public exploit code.

## Other vulnerabilities in Opensuse Leap

- [CVE-2015-4902](https://insights.sbomify.com/CVE-2015-4902/): Oracle Java SE Integrity Check (medium 5.3, exploited in the wild)
- [CVE-2017-14804](https://insights.sbomify.com/CVE-2017-14804/): package builds could use directory traversal to write outside of target area (critical 9.9)
- [CVE-2019-20787](https://insights.sbomify.com/CVE-2019-20787/): Teeworlds before 0.7.4 has an integer overflow when computing a tilemap size. (critical 9.8)
- [CVE-2019-8341](https://insights.sbomify.com/CVE-2019-8341/): Code injection in n/a (critical 9.8)
- [CVE-2019-6438](https://insights.sbomify.com/CVE-2019-6438/): Other in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-15691 and fix it if it is affected.

What it is: CVE-2019-15691 is a high-severity use after free vulnerability in Opensuse Leap, published on 26 Dec 2019. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-15691 in the wild and no public exploit code.

Affected product: Opensuse Leap. 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-2019-15691/ (Markdown: https://insights.sbomify.com/CVE-2019-15691/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-15691
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-15691
- OSV: https://osv.dev/vulnerability/CVE-2019-15691

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-15691/
Summaries are generated and may contain mistakes; the official description above is the record.