CVE-2026-26028Public exploitNetwork attack vector

HTML injection via unchecked iframe srcdoc

Published May 20, 2026 · Updated May 20, 2026

HTML injection in Diffmarked.js in XWiki CryptPad before 2026.2.0 allows remote attackers to inject interactive content into documents. The sanitizer checks only an iframe's src attribute, so a permitted blob source can accompany an unchecked srcdoc containing arbitrary HTML. A victim must open the crafted content, and the vendor reports that CryptPad's CSP blocks code execution at the browser level.

CVSS severity6.1
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTML injection in Diffmarked.js in XWiki CryptPad before 2026.2.0 allows remote attackers to inject interactive content into documents. The sanitizer checks only an iframe's src attribute, so a permitted blob source can accompany an unchecked srcdoc containing arbitrary HTML. A victim must open the crafted content, and the vendor reports that CryptPad's CSP blocks code execution at the browser level.

The record

CVE
CVE-2026-26028
Published
May 20, 2026
Updated
May 20, 2026
Vendor
CryptPad
Product
CryptPad
Classifications
CWE-79, CWE-116, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 20, 2026CVE publishedPublication date reported by the CVE source.
  2. May 20, 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=< 2026.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

CryptPad · CryptPadversion=< 2026.2.0

Published CVSS scores

6.1GitHub, Inc.CVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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')
CWE-116Improper Encoding or Escaping of Output
T1204.002Malicious File

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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