CVE-2020-1927Network attack vector

Open redirect via encoded newline in rewrite back-reference

Published Apr 1, 2020 · Updated Aug 4, 2024

Open redirect in mod_rewrite in Apache HTTP Server 2.4.0 through 2.4.41 allows remote attackers to redirect users via crafted URLs. Self-referential RewriteRule redirects process percent-decoded URL-path back-references, so an encoded newline makes the resulting Location value point to an attacker-controlled site. Exploitation requires a vulnerable rewrite rule and user interaction; the bounded consequence is navigation away from the trusted site.

CVSS severity6.1
Medium
EPSS probability56.69%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in mod_rewrite in Apache HTTP Server 2.4.0 through 2.4.41 allows remote attackers to redirect users via crafted URLs. Self-referential RewriteRule redirects process percent-decoded URL-path back-references, so an encoded newline makes the resulting Location value point to an attacker-controlled site. Exploitation requires a vulnerable rewrite rule and user interaction; the bounded consequence is navigation away from the trusted site.

The record

CVE
CVE-2020-1927
Published
Apr 1, 2020
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
CWE-601
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 1, 2020CVE 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=2.4.0 to 2.4.41

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=2.4.0 to 2.4.41

Published CVSS scores

6.1GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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.

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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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')

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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