CVE-2021-36373

Build crash via unchecked PAX header length

Published Jul 14, 2021 · Updated Aug 4, 2024

Resource exhaustion in Apache Ant 1.9.0 through 1.9.15 and 1.10.0 through 1.10.10 allows attackers to crash builds via crafted TAR archives. TarInputStream.parsePaxHeaders trusts the PAX record's declared length and allocates a byte array for the claimed remainder before confirming that the archive contains those bytes. The archive must be supplied to a build that reads or updates it; a forged length can exhaust the Java heap and terminate that build.

CVSS severity5.5
Medium
EPSS probability2.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Apache Ant 1.9.0 through 1.9.15 and 1.10.0 through 1.10.10 allows attackers to crash builds via crafted TAR archives. TarInputStream.parsePaxHeaders trusts the PAX record's declared length and allocates a byte array for the claimed remainder before confirming that the archive contains those bytes. The archive must be supplied to a build that reads or updates it; a forged length can exhaust the Java heap and terminate that build.

The record

CVE
CVE-2021-36373
Published
Jul 14, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Ant
Classifications
CWE-130, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 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=Apache Ant 1.10.x <=1.10.10 changes=[{"at":"1.10.0","status":"affected"}]
  2. Affected versionversion=Apache Ant 1.9.x <=1.9.15 changes=[{"at":"1.9.0","status":"affected"}]

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Antversion=Apache Ant 1.10.x <=1.10.10 changes=[{"at":"1.10.0","status":"affected"}]; version=Apache Ant 1.9.x <=1.9.15 changes=[{"at":"1.9.0","status":"affected"}]

Published CVSS scores

5.5NIST National Vulnerability DatabaseCVSS: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-130Improper Handling of Length Parameter Inconsistency
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

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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