# CVE-2026-120500: An Otter Wiki before 2.26.2 Stored XSS via Math Code Block

Status: published. Published: 2026-11-02. Updated: 2026-11-02.

An Otter Wiki before 2.26.2 contains a stored cross-site scripting vulnerability in OtterwikiMdRenderer.block_code that allows attackers who can edit pages, including anonymous users under the default configuration, to inject arbitrary script. Attackers can place HTML inside a math fenced code block, which is rendered unescaped and executes for every viewer of the page.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/redimp/otterwiki/commit/b2e91d20ed36c01ce140d18698f9abb90685d481

## Affected products and versions

- redimp / otterwiki (otterwiki): ≥ 2.0.0; < 2.26.2 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 6.1 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 6.1 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-79

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/redimp/otterwiki/commit/b2e91d20ed36c01ce140d18698f9abb90685d481 (CNA: VulnCheck; patch)

- https://github.com/redimp/otterwiki/releases/tag/v2.26.2 (CNA: VulnCheck; release-notes)

- https://www.vulncheck.com/advisories/an-otter-wiki-before-2.26.2-stored-xss-via-math-code-block (CNA: VulnCheck; third-party-advisory)

- https://github.com/redimp/otterwiki/commit/b2e91d20ed36c01ce140d18698f9abb90685d481 (disclosure@vulncheck.com)

- https://github.com/redimp/otterwiki/releases/tag/v2.26.2 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/an-otter-wiki-before-2.26.2-stored-xss-via-math-code-block (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-120500; retrieved 2026-11-02; source updated 2026-11-02

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-120500; retrieved 2026-11-02; source updated 2026-11-02

Revision: edd76c2761778bc6054ddce98a3246953b3287423251fd04ec9ba6f42623a401

Canonical: https://y2.dev/cve/CVE-2026-120500

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.