CVE-2025-40631Network attack vector

JavaScript execution via unneutralized Host header

Published May 16, 2025 · Updated May 16, 2025

HTTP host header injection in IceWarp Server 11.4.0 allows remote attackers to execute JavaScript after a user opens a malicious link. The web interface incorporates an attacker-controlled Host header containing script syntax into a page that executes when loaded; public details do not identify the endpoint or function. No authentication is required, but the target must follow the crafted link, and the resulting script can read or alter data in the browser context.

CVSS severity2.0
Low
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP host header injection in IceWarp Server 11.4.0 allows remote attackers to execute JavaScript after a user opens a malicious link. The web interface incorporates an attacker-controlled Host header containing script syntax into a page that executes when loaded; public details do not identify the endpoint or function. No authentication is required, but the target must follow the crafted link, and the resulting script can read or alter data in the browser context.

The record

CVE
CVE-2025-40631
Published
May 16, 2025
Updated
May 16, 2025
Vendor
IceWarp
Product
IceWarp Server
Classifications
CWE-644, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 16, 2025CVE publishedPublication date reported by the CVE source.
  2. May 16, 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=11.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

IceWarp · IceWarp Serverversion=11.4.0

Published CVSS scores

6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
2.0INCIBECVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA: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-644Improper Neutralization of HTTP Headers for Scripting Syntax
T1204.001User Execution: Malicious Link

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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