TI-2026-21042 Aliases CVE-2026-26028 GHSA-g2g4-47gv-p72v

CryptPad: Sanitizer Bypass in Diffmarked.js Allows Arbitrary HTML Injection and Potential XSS

LOW 27CWE-116Published 2026-05-20 · Updated 2026-05-20

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: Cross-site scripting
Confidentiality · integrity · availability: Low · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.

Summary

CryptPad is an end-to-end encrypted collaborative office suite. In versions prior to 2026.2.0, the HTML sanitizer in Diffmarked.js can be bypassed due to incomplete attribute filtering on restricted tags. The sanitizer validates only the src attribute of <iframe>, <video>, and <audio> elements, leaving all other attributes unchecked. As a result, an attacker can inject arbitrary HTML through srcdoc, completely defeating CryptPad's intended bounce sandboxing and enabling link injection or other interactive content within user-controlled documents. The root cause lies in how the sanitizer classifies and enforces tag restrictions: although it defines both forbidden and restricted tag lists, <iframe> is treated as "restricted" rather than "forbidden." Enforcement then inspects only the src attribute, so pairing a benign blob: src with a malicious srcdoc results in unrestricted rendering. This issue has been fixed in version 2026.2.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00242 15th percentileScored 2026-11-07

Fix Fixed cryptpad (cryptpad): 2026.2.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
XWiki	cryptpad	before 2026.2.0	2026.2.0	Patch available	CNA
—	cryptpad (npm)	up to 5.9.0	—	No fix listed	GHSA-g2g4-47gv-p72v

cryptpad VendorXWiki Affected before 2026.2.0 Fixed in 2026.2.0 Patch available CNA
cryptpad (npm) Vendor— Affected up to 5.9.0 Fixed in — No fix listed GHSA-g2g4-47gv-p72v

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:xwiki:cryptpad::::::::	—	—	XWiki

cpe:2.3:a:xwiki:cryptpad:*:*:*:*:*:*:*:* Versions — — ·XWiki

Remediation

Fix · CNA cryptpad (cryptpad) Fixed in 2026.2.0

Timeline

2026-10-02 Threatist record created from CVE-2026-26028
2026-10-03 Alias added: GHSA-g2g4-47gv-p72v

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-26028

Other 3

TI-2025-18595 Remote code execution as guest via SolrSearchMacros request in xwiki KEVCVSS 3.1CRITICAL 9.8
TI-2023-25214 Remote code execution through the section parameter in Administration as guest in XWiki Platform CVSS 3.1CRITICAL 10.0
TI-2025-23500 XWiki Platform vulnerable to SQL injection through getdeleteddocuments.vm template sort parameter CVSS 4.0CRITICAL 9.3
TI-2025-23979 org.xwiki.platform:xwiki-platform-rest-server allows SQL injection in query endpoint of REST API CVSS 4.0CRITICAL 9.3
TI-2024-20829 XWiki Platform: Remote code execution from account via SearchSuggestSourceSheet CVSS 3.1CRITICAL 10.0
TI-2024-14375 XWiki Remote Code Execution vulnerability via user registration CVSS 3.1CRITICAL 10.0

See all 304 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences