CVE-2021-39929Public exploitNetwork attack vector

Denial of service via nonadvancing recursive parsing

Published Nov 19, 2021 · Updated Aug 4, 2024

Uncontrolled recursion in Wireshark 3.2.0 through 3.2.17 and 3.4.0 through 3.4.9 allows attackers to crash it via malformed DHT data. The Bluetooth DHT dissector's dissect_bencoded_list function can revisit malformed nested bencoded list and dictionary data without advancing its offset, repeatedly recursing until the process stack overflows. Remote attackers can trigger the crash by injecting a malformed packet during live capture; the crafted-capture-file path requires a user to open the trace.

CVSS severity7.5
High
EPSS probability3.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in Wireshark 3.2.0 through 3.2.17 and 3.4.0 through 3.4.9 allows attackers to crash it via malformed DHT data. The Bluetooth DHT dissector's dissect_bencoded_list function can revisit malformed nested bencoded list and dictionary data without advancing its offset, repeatedly recursing until the process stack overflows. Remote attackers can trigger the crash by injecting a malformed packet during live capture; the crafted-capture-file path requires a user to open the trace.

The record

CVE
CVE-2021-39929
Published
Nov 19, 2021
Updated
Aug 4, 2024
Vendor
Wireshark Foundation
Product
Wireshark
Classifications
CWE-674, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=>=3.2.0, <3.2.18
  2. Affected versionversion=>=3.4.0, <3.4.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wireshark Foundation · Wiresharkversion=>=3.2.0, <3.2.18; version=>=3.4.0, <3.4.10

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
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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