ApostropheCMS is an open-source Node.js content management system. Versions 4.28.0 and prior contain a stored cross-site scripting vulnerability in SEO-related fields (SEO Title and Meta Description), where user-controlled input is rendered without proper output encoding into HTML contexts including tags, attributes, and JSON-LD structured data. An attacker can inject a payload such as ">alert(1) to break out of the intended HTML context and execute arbitrary JavaScript in the browser of any authenticated user who views the affected page. This can be leveraged to perform authenticated API requests, access sensitive data such as usernames, email addresses, and roles via internal APIs, and exfiltrate it to an attacker-controlled server. This issue has been fixed in version 4.29.0.
CVE-2026-35569
This high-severity CVE scores 8.7 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 78% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.7
- EG Score
- 8.7(medium)
- EG Risk
- 55(Track*)EG Risk 55/100SSVC: Track*
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity87% × 45%Exploitation40% × 40%Automatability0% × 15%Action: Watch closely — could escalate to Attend. - EPSS
- 21.9%
- KEV
- Not listed
Published
April 15, 2026
Last Modified
April 30, 2026
Advisory Details (3)
Auto-updated Apr 30, 2026Stored XSS in SEO Fields Leads to Authenticated API Data Exposure in ApostropheCMS · Advisory · apostrophecms/apostrophe · GitHub
https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-855c-r2vq-c292Merge commit from fork · apostrophecms/apostrophe@0e57dd0 · GitHub
https://github.com/apostrophecms/apostrophe/commit/0e57dd07a56ae1ba1e3af646ba026db4d0ab5bb3cve-research/CVE-2026-35569 at main · Chittu13/cve-research · GitHub
https://github.com/Chittu13/cve-research/tree/main/CVE-2026-35569Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| apostrophe | — | 4.29.0 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 40× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 03:10 UTCEG score recompute
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Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-35569?
When was CVE-2026-35569 disclosed?
Is CVE-2026-35569 actively exploited?
What is the CVSS score of CVE-2026-35569?
How do I remediate CVE-2026-35569?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-35569
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