CVE-2021-35438Public exploitNetwork attack vector

Browser script execution via unescaped calculator input

Published Jun 23, 2021 · Updated Feb 13, 2026

Reflected XSS in the phpIPAM 1.4.3 IP calculator allows remote attackers to execute script in a user's browser through crafted input. The two result scripts insert a submitted CIDR value into the calculator response without neutralizing embedded script markup. Exploitation requires user interaction, and successful script execution can read or alter data available to the affected page in that browser.

CVSS severity6.1
Medium
EPSS probability1.01%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in the phpIPAM 1.4.3 IP calculator allows remote attackers to execute script in a user's browser through crafted input. The two result scripts insert a submitted CIDR value into the calculator response without neutralizing embedded script markup. Exploitation requires user interaction, and successful script execution can read or alter data available to the affected page in that browser.

The record

CVE
CVE-2021-35438
Published
Jun 23, 2021
Updated
Feb 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2026Record 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
6.1NIST NVDCVSS: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.

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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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