CVE-2021-3688Network attack vector

Backend information disclosure via unnormalized proxy paths

Published Aug 26, 2022 · Updated Aug 3, 2024

Path traversal in Red Hat JBoss Core Services Apache HTTP Server before 2.4.37 SP10 allows remote attackers to access backend content. The mod_proxy path handler forwards dot-dot-semicolon segments without normalization, causing an otherwise excluded backend path to be proxied. Exploitation requires a mapping for the leading path and a backend server; the bypass exposes content at a path that should not be proxied.

CVSS severity4.8
Medium
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Red Hat JBoss Core Services Apache HTTP Server before 2.4.37 SP10 allows remote attackers to access backend content. The mod_proxy path handler forwards dot-dot-semicolon segments without normalization, causing an otherwise excluded backend path to be proxied. Exploitation requires a mapping for the leading path and a backend server; the bypass exposes content at a path that should not be proxied.

The record

CVE
CVE-2021-3688
Published
Aug 26, 2022
Updated
Aug 3, 2024
Vendor
Red Hat
Product
Red Hat JBoss Core Services Apache HTTP Server
Classifications
CWE-22, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 26, 2022CVE 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

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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=Fixed in jbcs-httpd-2.4.37.SP10 GA

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Red Hat · Red Hat JBoss Core Services Apache HTTP Serverversion=Fixed in jbcs-httpd-2.4.37.SP10 GA

Published CVSS scores

4.8Red Hat, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

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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