CVE-2026-76921Public exploit

Denial of service via stale top_tree reuse

Published Aug 19, 2026 · Updated Aug 20, 2026

Use after free in Wireshark's CMS dissector in 4.6.0 through 4.6.7 and 4.4.0 through 4.4.17 allows attackers to crash Wireshark via malformed CMS input. The ContentInfo decoder stores a packet tree in the file-static top_tree pointer, fails to clear it when BER parsing throws a bounds exception, and later passes that freed tree into eContent OID callback dispatch. Exploitation requires malformed CMS data to reach the dissector, either by injecting packets onto a captured network or by supplying a crafted capture file, and the published impact is a process crash rather than code execution.

CVSS severity5.5
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use after free in Wireshark's CMS dissector in 4.6.0 through 4.6.7 and 4.4.0 through 4.4.17 allows attackers to crash Wireshark via malformed CMS input. The ContentInfo decoder stores a packet tree in the file-static top_tree pointer, fails to clear it when BER parsing throws a bounds exception, and later passes that freed tree into eContent OID callback dispatch. Exploitation requires malformed CMS data to reach the dissector, either by injecting packets onto a captured network or by supplying a crafted capture file, and the published impact is a process crash rather than code execution.

The record

CVE
CVE-2026-76921
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
Wireshark Foundation
Product
Wireshark
Classifications
CWE-416
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.4.0 <4.4.18
  2. Affected versionversion=4.6.0 <4.6.8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Wireshark Foundation · Wiresharkversion=4.4.0 <4.4.18; version=4.6.0 <4.6.8

Published CVSS scores

5.5GitLab Inc.CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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