# CVE-2026-18785: o6 open62541 client_types_custom.c UA_Client_getRemoteDataTypes use after free

> A use-after-free vulnerability in the open62541 library allows local attackers to potentially execute code or cause denial of service via the client types example.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/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:** No
- **Published:** 4 Aug 2026
- **Updated:** 4 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-18785, GHSA-vm49-7pv6-899p, UBUNTU-CVE-2026-18785

## What is CVE-2026-18785?

CVE-2026-18785 is a medium-severity use after free vulnerability in o6 open62541, published on 4 Aug 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 o6 open62541 ca356b088ada7dee824d1b4acd07c1ff07ce242b. Impacted is the function UA_Client_getRemoteDataTypes of the file examples/custom_datatype/client_types_custom.c. Executing a manipulation can lead to use after free. It is possible to launch the attack on the local host. The exploit has been publicly disclosed and may be utilized. The project closed the issue report, stating that this is not the official way to report a security vulnerability.

Weakness: CWE-416 (Use After Free), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-18785?


## How do I fix CVE-2026-18785?

No fix has been published for CVE-2026-18785 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-18785 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-18785 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18785 and fix it if it is affected.

What it is: CVE-2026-18785 is a medium-severity use after free vulnerability in o6 open62541, published on 4 Aug 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-2026-18785 exists.

Affected product: o6 open62541. 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-2026-18785/ (Markdown: https://insights.sbomify.com/CVE-2026-18785/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18785
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18785
- OSV: https://osv.dev/vulnerability/CVE-2026-18785

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18785/
Summaries are generated and may contain mistakes; the official description above is the record.