# CVE-2026-128044: OpenMage magento-lts before 20.18.2 OAuth Callback URL Allowlist Bypass

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

OpenMage magento-lts before 20.18.2 and 21.x before 21.0.0-beta3 validates OAuth 1.0a oauth_callback URLs with a string-prefix check and falls back to accepting any well-formed URL. Attackers holding a leaked consumer key and secret can supply host-suffix, userinfo, or arbitrary callback URLs to capture an approving administrator's or customer's request token and verifier, then obtain an access token with the victim's API privileges.

## 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/OpenMage/magento-lts/commit/d03a00b60e4a2d4e5a00b44dbc66d25bc3b3fc8f

## Affected products and versions

- OpenMage / magento-lts: ≥ 0; < 20.18.2 (affected, semver); 20.18.2 (unaffected, semver). Source: CNA: VulnCheck
- OpenMage / magento-lts: ≥ 21.0.0-beta1; < 21.0.0-beta3 (affected, semver); 21.0.0-beta3 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.7 (high); CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N; source: CNA: VulnCheck

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/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: 7.7 (high); CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-346

## Exploit evidence

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

## References

- https://github.com/OpenMage/magento-lts/security/advisories/GHSA-mffc-h5pf-6f42 (CNA: VulnCheck; vendor-advisory)

- https://github.com/OpenMage/magento-lts/commit/d03a00b60e4a2d4e5a00b44dbc66d25bc3b3fc8f (CNA: VulnCheck; patch)

- https://www.vulncheck.com/advisories/openmage-magento-lts-before-20.18.2-oauth-callback-url-allowlist-bypass (CNA: VulnCheck; third-party-advisory)

- https://github.com/OpenMage/magento-lts/commit/d03a00b60e4a2d4e5a00b44dbc66d25bc3b3fc8f (disclosure@vulncheck.com)

- https://github.com/OpenMage/magento-lts/security/advisories/GHSA-mffc-h5pf-6f42 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/openmage-magento-lts-before-20.18.2-oauth-callback-url-allowlist-bypass (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-128044; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-128044; retrieved 2026-11-13; source updated 2026-11-13

Revision: 65c2d8b2c04357105b9109e93da283e492db85eb46dc40808ea7871cdea65245

Canonical: https://y2.dev/cve/CVE-2026-128044

## 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.