CVE-2021-4186Public exploitNetwork attack vector

Process crash via missing Gryphon packet state

Published Dec 30, 2021 · Updated Nov 3, 2025

NULL pointer dereference in Wireshark 3.4.0 through 3.4.10 allows remote attackers to crash the process with malformed Gryphon traffic. The Gryphon decode_response function assumes per-packet information exists during a second dissection pass and reads through a null pointer when unusual TCP sequencing leaves it absent. Packet injection requires traffic to reach an active capture; opening a crafted trace requires user interaction, and either path interrupts only the analyzing Wireshark or TShark process.

CVSS severity6.3
Medium
EPSS probability2.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Wireshark 3.4.0 through 3.4.10 allows remote attackers to crash the process with malformed Gryphon traffic. The Gryphon decode_response function assumes per-packet information exists during a second dissection pass and reads through a null pointer when unusual TCP sequencing leaves it absent. Packet injection requires traffic to reach an active capture; opening a crafted trace requires user interaction, and either path interrupts only the analyzing Wireshark or TShark process.

The record

CVE
CVE-2021-4186
Published
Dec 30, 2021
Updated
Nov 3, 2025
Vendor
Wireshark Foundation
Product
Wireshark
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 30, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record 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=>=3.4.0, <3.4.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wireshark Foundation · Wiresharkversion=>=3.4.0, <3.4.10

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:N/I:N/A:P
6.3GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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