# CVE-2026-67863: Use after free in n/a

> A remote attacker can cause a denial of service in open62541 by triggering a use-after-free in the local MonitoredItem callback path.

- **Severity:** High 7.5 (`CVSS:3.1/AC:L/AV:N/A:H/C:N/I:N/PR:N/S:U/UI:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Aug 2026
- **Updated:** 7 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-67863, GHSA-j8g3-2qjc-25x2, UBUNTU-CVE-2026-67863

## What is CVE-2026-67863?

CVE-2026-67863 is a high-severity use after free vulnerability in n/a, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In open62541 1.5.5, a server-side use-after-free exists in the local MonitoredItem callback path. The issue occurs when UA_Subscription_localPublish continues to use the current UA_Notification after a callback invokes UA_Server_deleteMonitoredItem for the current local MonitoredItem. This allows a remote attacker to cause a denial of service.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-67863?


## How do I fix CVE-2026-67863?

No fix has been published for CVE-2026-67863 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-67863 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67863 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-67863 and fix it if it is affected.

What it is: CVE-2026-67863 is a high-severity use after free vulnerability in n/a, published on 5 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-2026-67863 exists.

Affected product: n/a. 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-2026-67863/ (Markdown: https://insights.sbomify.com/CVE-2026-67863/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-67863
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-67863
- OSV: https://osv.dev/vulnerability/CVE-2026-67863

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-67863/
Summaries are generated and may contain mistakes; the official description above is the record.