CVE-2020-18976Public exploit

Process crash via unchecked checksum write

Published Aug 25, 2021 · Updated Aug 4, 2024

Heap buffer overflow in AppNeta Tcpreplay 4.3.2 allows local users to crash tcpreplay-edit by processing a crafted pcap file. The do_checksum function trusts the packet's IP header length without ensuring that the captured data contains a TCP header, then writes zero to a checksum field beyond the heap allocation. A local user must run tcpreplay-edit on the malicious capture; the demonstrated result is a process abort, with no reported data disclosure or code execution.

CVSS severity5.5
Medium
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in AppNeta Tcpreplay 4.3.2 allows local users to crash tcpreplay-edit by processing a crafted pcap file. The do_checksum function trusts the packet's IP header length without ensuring that the captured data contains a TCP header, then writes zero to a checksum field beyond the heap allocation. A local user must run tcpreplay-edit on the malicious capture; the demonstrated result is a process abort, with no reported data disclosure or code execution.

The record

CVE
CVE-2020-18976
Published
Aug 25, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5NIST NVDCVSS: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-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1204.002Malicious File

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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