Stored XSS in ApostropheCMS via unescaped widget style attribute
Key facts
- Attack vector
- Network
- Privileges required
- Low
- 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
ApostropheCMS apostrophe npm package before 4.34.0 is affected. Its wrapper serializer does not HTML-encode a project-defined free-form widget style field, so a quote from an editor can break out of the inline style attribute (CWE-79). A low-privileged editor can store script that runs in the browser of a user who views the rendered published content or an affected draft.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
Description from the CNA
ApostropheCMS is an open-source Node.js content management system. Prior to 4.34.0, a project-defined free-form widget style field can carry an editor-controlled quote into an inline style attribute because the wrapper serializer does not apply HTML-attribute encoding. The quote can terminate the style attribute and inject executable attributes when published content, or an affected draft viewed by a higher-privileged user, is rendered. This issue is fixed in version 4.34.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- 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 |
|---|---|---|---|---|---|
| apostrophecms | apostrophe | before 4.34.0 | 4.34.0 | Patch available | CNA |
| — | apostrophe (npm) | before 4.34.0 | 4.34.0 | Patch available | GHSA-7jg5-frgc-c67w |
- apostrophe Vendorapostrophecms Affected before 4.34.0 Fixed in 4.34.0 Patch available CNA
- apostrophe (npm) Vendor— Affected before 4.34.0 Fixed in 4.34.0 Patch available GHSA-7jg5-frgc-c67w
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:apostrophecms:apostrophecms:*:*:*:*:*:*:*:* | — | — | apostrophecms |
- cpe:2.3:a:apostrophecms:apostrophecms:*:*:*:*:*:*:*:* Versions — — ·apostrophecms
Remediation
Upgrade the npm package apostrophe to version 4.34.0, which fixes this issue. The sources list no fixed version for the apostrophecms vendor entry, but the npm entry for apostrophe lists 4.34.0 as fixed.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
- Fix · CNA apostrophe (apostrophecms) Fixed in 4.34.0
- Fix · GHSA-7jg5-frgc-c67w apostrophe (npm) Fixed in 4.34.0 Advisory →
Timeline
- 2026-10-20 Threatist record created from CVE-2026-112958
- 2026-10-20 CISA SSVC decision points changed
- 2026-10-21 Alias added: GHSA-7jg5-frgc-c67w
- 2026-10-21 Fix available: npm/[email protected] · GHSA-7jg5-frgc-c67w
- 2026-10-21 CVSS score added · GHSA-7jg5-frgc-c67w
- 2026-10-21 Weakness changed · GHSA-7jg5-frgc-c67w
- 2026-10-21 6 new references · GHSA-7jg5-frgc-c67w
References
Other 5
- https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-7jg5-frgc-c67w
- https://github.com/apostrophecms/apostrophe/commit/06e4b377f3c360f9e89c32dccd7e505ad5ddf498
- https://github.com/apostrophecms/apostrophe/commit/40b989b1a9dd23d30029b8ce7668634265cfe5ea
- https://github.com/apostrophecms/apostrophe/releases/tag/[email protected]
- https://github.com/apostrophecms/apostrophe
More apostrophecms vulnerabilities
- TI-2026-25223 ApostropheCMS has Arbitrary File Write (Zip Slip / Path Traversal) in Import-Export Gzip Extraction CVSS 3.1CRITICAL 10.0
- TI-2026-32848 Apostrophe has default XSS via `xmp` raw-text passthrough in `sanitize-html` CVSS 3.1CRITICAL 9.3
- TI-2026-38664 @apostrophecms/seo Vulnerable to Stored XSS via Unsanitized Google Analytics / GTM ID Injected into Script Tag CVSS 3.1HIGH 8.7
- TI-2026-27673 ApostropheCMS: Stored XSS in SEO Fields Leads to Authenticated API Data Exposure in ApostropheCMS CVSS 3.1HIGH 8.7
- TI-2026-76992 Unauthenticated resource exhaustion via ApostropheCMS import routes CVSS 3.1HIGH 7.5
- TI-2026-76974 ApostropheCMS leaves rejected CSV uploads in temporary directory CVSS 3.1HIGH 7.5
Sources
- CVE-2026-112958 · CVE Program
- CVE-2026-112958 · NVD
- FIRST EPSS
- GHSA-7jg5-frgc-c67w · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences