ProseMirror prosemirror-view: Cross-Site Scripting in paste handling
Summary
prosemirror-view, the view component of the ProseMirror rich-text editor toolkit, does not validate attributes supplied via the clipboard slice context when HTML is pasted. A user who pastes crafted HTML into an affected editor can cause attacker-controlled JavaScript to run in the browser window containing the editor. The attacker needs the victim to paste the content, and the impact is limited to the editor's browser context, for example session data or actions inside a logged-in application.
Affected
- prosemirror-view versions before 1.42.3 (npm)
- Applications and frameworks that bundle a vulnerable prosemirror-view, for example TipTap-based editors or Atlassian Forge UI Kit apps (transitive dependency)
Fixed in
- Upgrade to prosemirror-view 1.42.3 or later
- Upgrade prosemirror-model together with prosemirror-view (1.42.3 requires prosemirror-model ^1.25.8)
Workaround
No known workarounds according to the vendor advisory. Upgrading is the only documented remedy.
Exploitation
- Not known to be exploited in the wild.
- CISA SSVC: exploitation none, not automatable.
- EPSS 0.00305 (low).
- No public proof of concept found; not verified in depth.
Our recommendation
- Identify all applications that use prosemirror-view, directly or transitively, and check lockfiles and dependency trees for versions below 1.42.3.
- Update to 1.42.3 or later together with prosemirror-model, then test the editor, including paste.
- If an update is not possible in the short term, restrict editing to trusted users and consider a strict Content Security Policy to limit script execution.
- Monitor vendor advisories and changelogs for later releases.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-c8x8-7fp4-3x9w github.com
- Fix commit: Validate attributes provided via clipboard slice context github.com
- Fix commit: Mark version 1.42.3 (changelog) github.com
- GitLab Advisory Database entry advisories.gitlab.com
- VulDB entry vuldb.com
- HOL Guard CVE entry hol.org
- Atlassian Developer Community: Forge dependencies pin vulnerable prosemirror-view community.developer.atlassian.com
- Outline pull request: prosemirror-view 1.42.3 upgrade notes github.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 11:33.
Original description (NVD)
ProseMirror's view component renders and manages the editable browser interface for ProseMirror documents. Prior to 1.42.3, prosemirror-view paste handling accepts attacker-provided HTML whose clipboard slice context contains attributes that are not passed through schema attribute validation. When a user pastes the crafted HTML into an editor, the unvalidated context attributes can construct content that executes attacker-controlled JavaScript in the browser window containing the editor. This issue is fixed in version 1.42.3.
NVD references (6)
- https://github.com/ProseMirror/prosemirror-view/commit/20dc0a911a79f8fc6640dbbea5e7d68d3c4784b7
- https://github.com/ProseMirror/prosemirror-view/commit/2e91a612bbc1248e55b4f6061fc93fe459f977c1
- https://github.com/ProseMirror/prosemirror-view/security/advisories/GHSA-c8x8-7fp4-3x9w
- https://github.com/ProseMirror/prosemirror-view/security/advisories/GHSA-c8x8-7fp4-3x9w
- https://github.com/ProseMirror/prosemirror-view/security/advisories/GHSA-c8x8-7fp4-3x9w
- https://github.com/ProseMirror/prosemirror-view/security/advisories/GHSA-c8x8-7fp4-3x9w
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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