CVE-2025-27820Network attack vector

Domain validation bypass via relative PSL resource path

Published Apr 24, 2025 · Updated Jun 4, 2025

PSL validation bypass in Apache HttpClient 5.4.0 through 5.4.2 allows remote attackers to bypass domain checks in HTTP clients. PublicSuffixMatcherLoader.getDefault resolves the bundled PSL through Class.getResource with a relative path, yielding a nearly empty matcher when the resource is not found. Applications using the default matcher then lose intended cookie-domain and host name verification enforcement.

CVSS severity7.5
High
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

PSL validation bypass in Apache HttpClient 5.4.0 through 5.4.2 allows remote attackers to bypass domain checks in HTTP clients. PublicSuffixMatcherLoader.getDefault resolves the bundled PSL through Class.getResource with a relative path, yielding a nearly empty matcher when the resource is not found. Applications using the default matcher then lose intended cookie-domain and host name verification enforcement.

The record

CVE
CVE-2025-27820
Published
Apr 24, 2025
Updated
Jun 4, 2025
Vendor
The Apache Software Foundation
Product
Apache HttpComponents
Classifications
CWE-295
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 4, 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=5.4.0 <5.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HttpComponentsversion=5.4.0 <5.4.3

Published CVSS scores

7.5CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation

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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