# CVE-2026-12067: Avast Antivirus denial of service in AvastSvc message dispatcher

Source: https://junglewise.ai/threats/cve-2026-12067-missing-exception-handlers-in-avastsvc-native-message-dispatcher  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-06. Updated: 2026-11-06  
License: CC BY 4.0 with a link back

CVE-2026-12067 · Severity: info · Published 2026-11-06

Avast Antivirus contains a flaw in its AvastSvc native message dispatcher (ashServ.dll) that allows a local user to crash the service by sending specially crafted JSON messages. An attacker with local access could repeatedly trigger this crash to disable antivirus protection on a Windows system.

Technologies: [Avast Antivirus](https://junglewise.ai/threats/technologies/avast-antivirus-1). Vendors: [Avast](https://junglewise.ai/threats/vendors/avast).

## Quick answers

**Is CVE-2026-12067 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12067 being exploited in the wild.

**How severe is CVE-2026-12067?** Informational severity, published 6 November 2026.

**Which products and versions are affected?** Avast Antivirus <UNKNOWN>.

**Is there a fix for CVE-2026-12067?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-12067 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-12067?** Check whether you run Avast Antivirus at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability stems from missing exception handlers in three JSON message processing pathways (Log_NmSvc, OpenInSz_NmSvc, and OpenInSz_NmSvc.profile handlers) within the RPC-based native message protocol. Type conversions on untrusted JSON fields are performed without validation or try-catch blocks, allowing uncaught exceptions to propagate and crash the dispatcher. An unprivileged local attacker can exploit this via specially crafted JSON messages sent through the RPC interface.

## Affected products

- Avast Antivirus <UNKNOWN>

## Timeline

- 2026-11-06: advisory

## References

- [https://support.avast.com/en-us/article/Update-Antivirus](https://support.avast.com/en-us/article/Update-Antivirus)
- [https://support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus](https://support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus)

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