CVE-2021-30641Network attack vector

Unauthenticated request-handling alteration via repeated slashes

Published Jun 10, 2021 · Updated Aug 3, 2024

URL-matching error in Apache HTTP Server 2.4.39 through 2.4.46 allows remote attackers to alter request handling via repeated slashes. The vendor has not published the exact code locus or incorrect matching operation beyond unexpected behavior when MergeSlashes is OFF. Exposure requires that nondefault setting; public records establish only low integrity impact and do not identify the affected resource operation.

CVSS severity5.3
Medium
EPSS probability52.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

URL-matching error in Apache HTTP Server 2.4.39 through 2.4.46 allows remote attackers to alter request handling via repeated slashes. The vendor has not published the exact code locus or incorrect matching operation beyond unexpected behavior when MergeSlashes is OFF. Exposure requires that nondefault setting; public records establish only low integrity impact and do not identify the affected resource operation.

The record

CVE
CVE-2021-30641
Published
Jun 10, 2021
Updated
Aug 3, 2024
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.4.39
  2. Affected versionversion=2.4.41
  3. Affected versionversion=2.4.43
  4. Affected versionversion=2.4.46

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=2.4.39; version=2.4.41; version=2.4.43; version=2.4.46

Published CVSS scores

5.3NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

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

No sourced classifications are available.

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo