# CVE-2026-8890: code100x Mobile API Authentication Bypass via Header Spoofing

Status: published. Published: 2026-05-26. Updated: 2026-11-08.

code100x contains an authentication bypass vulnerability in the Mobile API that allows unauthenticated attackers to impersonate arbitrary users by supplying a crafted JSON payload in the 'g' HTTP header. The middleware in middleware.ts skips identity header generation when an Auth-Key header is present without validating its value, allowing attackers to inject a spoofed user identity header that the downstream route handler in the mobile courses endpoint accepts as trusted, granting unauthorized access to course data belonging to any enrolled user or administrator.

## 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/code100x/cms/pull/1927
- 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/code100x/cms/pull/1927/changes/90b489ee7c63c301107d6374d4b3f2b8e4060fe5
- 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/code100x/cms/pull/1927/changes/88c6c5e94e23da101235c4c7e9c7591ac1016549

## Affected products and versions

- code100x / code100x: ≥ 0; < 90b489ee7c63c301107d6374d4b3f2b8e4060fe5 (affected, custom); ≥ 0; < 88c6c5e94e23da101235c4c7e9c7591ac1016549 (affected, custom). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 8.8 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.49% as of 2026-11-08; percentile 42.43%

- SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-639

## Exploit evidence

- exploit: https://github.com/code100x/cms/issues/1924 (ADP: CISA-ADP)
- exploit: https://github.com/code100x/cms/pull/1927 (ADP: CISA-ADP)

## References

- https://github.com/code100x/cms/issues/1924 (CNA: VulnCheck; issue-tracking)

- https://github.com/code100x/cms/pull/1927 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/code100x/cms/pull/1927/changes/90b489ee7c63c301107d6374d4b3f2b8e4060fe5 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/code100x/cms/pull/1927/changes/88c6c5e94e23da101235c4c7e9c7591ac1016549 (CNA: VulnCheck; issue-tracking, patch)

- https://www.vulncheck.com/advisories/code100x-mobile-api-authentication-bypass-via-header-spoofing (CNA: VulnCheck; third-party-advisory)

- https://github.com/code100x/cms/issues/1924 (ADP: CISA-ADP; exploit)

- https://github.com/code100x/cms/pull/1927 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-8890; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-8890; retrieved 2026-11-08; source updated Not reported

Revision: 0b04edce498f684ba247a56efbaf5071b4c0aaa63b47894fcf66c8e8b54fb373

Canonical: https://y2.dev/cve/CVE-2026-8890

## 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.