CVE-2026-86644
CVE-2026-86644 — star7th showdoc API Page Save Endpoint editormd.js cross site scripting
A vulnerability was determined in star7th showdoc up to 3.9.1. This vulnerability affects unknown code of the file web_src/public/editor.md/editormd.js of the component API Page Save Endpoint. Executing a manipulation can lead to cross site scripting. The attack may be launched remotely. The exploit has been publicly disclosed and may be utilized. Upgrading to version 3.9.2 is able to resolve this issue. This patch is called a8ea1520850b4242f395247f72e87e597506cef0. Upgrading the affected component is recommended. The vendor confirms: "The fix [...] sets Mermaid `securityLevel` to `strict`, disables `htmlLabels`, and sanitizes rendered SVG with DOMPurify."
Published Updated Sources: cvelistV5, VulDB
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
0%
chance of exploitation in 30 days
CVSS base
3.5
LOW
CISA SSVC assessment
Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.
Exploitation
PoC
none · proof-of-concept · active
Automatable
No
can an attacker script all four kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component
Affected scope
The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.
Vendors (1)
Products (1)
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 3.5 | CVSS 3.1 | LOW | — | — | cvelistV5 |
Weakness & attack patterns
- CWE-79
- CWE-94
Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.
- T1027.006Obfuscated Files or Information: HTML Smuggling
- T1027.009Obfuscated Files or Information: Embedded Payloads
- T1564.009Hide Artifacts: Resource Forking
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /public/editor.md/editormd.js.
References
8 on the record
- vuldb.com/vuln/399755
vdb-entry
- vuldb.com/vuln/399755/cti
signature, permissions-required
- vuldb.com/cve/CVE-2026-86644
third-party-advisory
- vuldb.com/submit/906282
third-party-advisory
- gist.github.com/saDL0w/36a72a076e9ab24408a3d27582e778b2
exploit
- github.com/star7th/showdoc/commit/a8ea1520850b4242f395247f72e87e597506cef0
patch
- github.com/star7th/showdoc/releases/tag/v3.9.2
patch
- github.com/star7th/showdoc/
product
Elsewhere on this site
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.