CVE-2025-5940Network attack vector

Stored XSS via unescaped class_name attribute

Published Jun 27, 2025 · Updated Apr 8, 2026

Stored XSS in OsomPress Osom Blocks 1.2.1 and earlier allows remote authenticated users to inject scripts through class_name. The CPT-list block renderer writes the stored class_name value into generated HTML without adequate input sanitization or output escaping. Contributor-level access is sufficient to plant the payload, which executes in another user's browser whenever the affected page is viewed.

CVSS severity6.4
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in OsomPress Osom Blocks 1.2.1 and earlier allows remote authenticated users to inject scripts through class_name. The CPT-list block renderer writes the stored class_name value into generated HTML without adequate input sanitization or output escaping. Contributor-level access is sufficient to plant the payload, which executes in another user's browser whenever the affected page is viewed.

The record

CVE
CVE-2025-5940
Published
Jun 27, 2025
Updated
Apr 8, 2026
Vendor
OsomPress
Product
Osom Blocks
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 27, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 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?

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

  1. Affected versionversion=0 <=1.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OsomPress · Osom Blocksversion=0 <=1.2.1

Published CVSS scores

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
6.4WordfenceCVSS:3.1/AV:N/AC:L/PR:L/UI:N/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

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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