CVE-2021-38751Public exploitNetwork attack vector

Link rewriting via unchecked Host header

Published Aug 16, 2021 · Updated Aug 4, 2024

Host header injection in ExponentCMS 2.6 and earlier allows remote attackers to rewrite generated links through a crafted HTTP Host header. In exponent_constants.php, the application accepts the unvalidated Host value and incorporates attacker-controlled text into links generated for the page. No authentication is required, but the integrity impact depends on a victim interacting with an attacker-rewritten link.

CVSS severity4.3
Medium
EPSS probability2.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Host header injection in ExponentCMS 2.6 and earlier allows remote attackers to rewrite generated links through a crafted HTTP Host header. In exponent_constants.php, the application accepts the unvalidated Host value and incorporates attacker-controlled text into links generated for the page. No authentication is required, but the integrity impact depends on a victim interacting with an attacker-rewritten link.

The record

CVE
CVE-2021-38751
Published
Aug 16, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-116, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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.

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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 exploitPublished

Weakness, pattern, technique

CWE-116Improper Encoding or Escaping of Output
T1565.002Transmitted Data Manipulation

Public exploit references

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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