CVE-2021-43082Network attack vector

Memory overwrite via unchecked Accept-Encoding length

Published Nov 3, 2021 · Updated Aug 4, 2024

Classic buffer overflow in Apache Traffic Server 9.1.0 stats-over-http allows remote attackers to overwrite process memory via HTTP. The plugin searches an Accept-Encoding header for a supported coding without first ensuring that the field is long enough for that search. The plugin must be enabled and its statistics endpoint reachable; published evidence establishes memory corruption but not code execution.

CVSS severity9.8
Critical
EPSS probability2.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Classic buffer overflow in Apache Traffic Server 9.1.0 stats-over-http allows remote attackers to overwrite process memory via HTTP. The plugin searches an Accept-Encoding header for a supported coding without first ensuring that the field is long enough for that search. The plugin must be enabled and its statistics endpoint reachable; published evidence establishes memory corruption but not code execution.

The record

CVE
CVE-2021-43082
Published
Nov 3, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Traffic Server
Classifications
CWE-120, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 3, 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=9.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Traffic Serverversion=9.1.0

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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