# CVE-2026-77709: SonicWall SonicOS heap buffer overflow in TACACS+ client

Source: https://junglewise.ai/threats/cve-2026-77709-a-pre-authentication-heap-based-buffer-overflow-vulnerability-has  
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-2026-77709 · Severity: info · Published 2026-11-06

SonicOS contains a heap buffer overflow flaw in its TACACS+ authentication client that can be triggered by a remote attacker without authentication. In specific conditions, this vulnerability could cause the authentication service to crash, leading to a denial of service where legitimate users cannot authenticate to the system.

Technologies: [SonicWall SonicOS](https://junglewise.ai/threats/technologies/sonicos). Vendors: [SonicWall](https://junglewise.ai/threats/vendors/sonicwall).

## Quick answers

**Is CVE-2026-77709 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-77709 being exploited in the wild.

**How severe is CVE-2026-77709?** Informational severity, published 6 November 2026.

**Which products and versions are affected?** SonicWall SonicOS.

**Is there a fix for CVE-2026-77709?** 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-2026-77709 attacked?** It is attacked over the network, in device firmware.

**Am I affected by CVE-2026-77709?** Check whether you run SonicWall SonicOS. 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

A pre-authentication heap-based buffer overflow exists in the SonicOS TACACS+ authentication client component. The vulnerability is exploitable over the network without requiring authentication, but specific preconditions must be met. Successful exploitation results in an application-level denial of service rather than code execution.

## Affected products

- SonicWall SonicOS

## Timeline

- 2026-11-06: disclosed

## References

- [https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2026-0014](https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2026-0014)

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- [SonicWall SonicOS stack-based buffer overflow in TACACS+ client](https://junglewise.ai/threats/cve-2026-77708-a-pre-authentication-stack-based-buffer-overflow-vulnerability)
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