CVE-2026-76885: Tektronix K12xx Parser DoS Vulnerability

CVE-2026-76885 Overview

CVE-2026-76885 is a denial-of-service vulnerability affecting the Tektronix K12xx file parser in Wireshark. The flaw exists in Wireshark versions 4.6.0 through 4.6.7 and 4.4.0 through 4.4.18. An attacker can trigger a parser crash by convincing a user to open or process a crafted K12xx capture file. Successful exploitation results in application termination, disrupting packet analysis workflows. The underlying weakness is classified as [CWE-126] Buffer Over-read. The issue is tracked in Wireshark Security Advisory WNPA-SEC-2026-71.

Critical Impact
A crafted Tektronix K12xx capture file causes Wireshark to crash, producing a denial of service for analysts relying on the tool for network forensics.

Affected Products

Wireshark 4.6.0 through 4.6.7
Wireshark 4.4.0 through 4.4.18
Tektronix K12xx file parser component

Discovery Timeline

2026-08-19 - CVE CVE-2026-76885 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-76885

Vulnerability Analysis

The vulnerability resides in the Wireshark dissector responsible for parsing Tektronix K12xx capture files. When Wireshark opens a malformed K12xx file, the parser reads memory beyond an intended buffer boundary. The read-past-end condition causes the application to crash, terminating the current analysis session and any unsaved state. Exploitation requires user interaction, since an analyst must open the crafted file or ingest it through an automated capture-processing pipeline. The impact is limited to availability; the advisory does not report confidentiality or integrity effects.

Root Cause

The defect is a buffer over-read [CWE-126] in the K12xx file parser. The parser accesses data past the end of an in-memory buffer while interpreting file structures, and the process aborts when the invalid access is detected. Full technical detail is tracked in GitLab Work Item #21414.

Attack Vector

Delivery is network-adjacent in practice: an attacker distributes a crafted .k12 or K12 text-format capture file through email, shared folders, ticketing systems, or public sample repositories. When an analyst opens the file in Wireshark or feeds it into tshark for batch processing, the parser aborts. Automated ingestion pipelines that call Wireshark libraries against untrusted captures may crash repeatedly, denying service until the offending file is quarantined.

No verified public exploit code is available. See the Wireshark Security Advisory WNPA-SEC-2026-71 for authoritative technical details.

Detection Methods for CVE-2026-76885

Indicators of Compromise

Unexpected wireshark or tshark process crashes correlated with opening .k12 or K12 text-format files
Presence of untrusted K12xx capture files delivered through email attachments or shared file services
Crash dumps or Windows Error Reporting entries referencing the Wireshark K12 dissector module

Detection Strategies

Monitor endpoint telemetry for abnormal termination of Wireshark and tshark processes on analyst workstations
Alert on inbound file transfers with K12xx capture file extensions from external or untrusted sources
Track installed Wireshark versions across the fleet and flag hosts running affected 4.4.x and 4.6.x builds

Monitoring Recommendations

Log all invocations of Wireshark command-line tools against externally sourced capture files
Instrument shared analysis sandboxes to capture stack traces when parser processes exit abnormally
Review SOC playbooks that automate capture ingestion to ensure malformed files do not halt processing queues

How to Mitigate CVE-2026-76885

Immediate Actions Required

Upgrade Wireshark to a version outside the affected ranges as directed by WNPA-SEC-2026-71
Inventory analyst workstations, forensic virtual machines, and automation servers running Wireshark 4.4.0–4.4.18 or 4.6.0–4.6.7
Instruct analysts to avoid opening K12xx capture files from untrusted sources until patched

Patch Information

The Wireshark Foundation addresses the defect in updates published alongside advisory WNPA-SEC-2026-71. Consult the Wireshark security advisory and the tracking issue at GitLab Work Item #21414 for fixed version identifiers and change details.

Workarounds

Disable or remove the Tektronix K12xx dissector where operationally feasible using Wireshark's Enabled Protocols configuration
Restrict capture-file ingestion pipelines to trusted internal sources until updates are deployed
Process suspicious captures in isolated, non-production analysis sandboxes to contain crash impact

bash

# Verify installed Wireshark version on Linux/macOS
wireshark --version | head -n 1
tshark --version | head -n 1

# On Windows (PowerShell)
Get-ItemProperty "HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*" |
  Where-Object { $_.DisplayName -like "Wireshark*" } |
  Select-Object DisplayName, DisplayVersion