CVE-2026-73563

MEDIUMPre-NVD 4.74.7—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 90% 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).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
4.7EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.7Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob matching for auth.experimentalDynamicClientRegistration.allowedRedirectUriPatterns and the auth.experimentalClientIdMetadataDocuments allowedClientIdPatterns and allowedRedirectUriPatterns options. A hostname wildcard can match across URL component boundaries, allowing an attacker-controlled redirect URI with a trusted hostname suffix in its path to pass the allowlist and receive an OAuth authorization code after a victim completes the flow. Patterns without an explicit protocol can match unintended protocols, and redirect URIs containing embedded credentials are accepted after user information is stripped for matching. The features are experimental and disabled by default; only deployments that enable them and configure custom wildcard-hostname or protocol-less patterns are affected. This issue is first fixed in prerelease version 0.29.2.

CVSS v3
4.7
EG Score
4.7(medium)
EG Risk
26(Track)
EG Risk 26/100SSVC: 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 computed
Severity47% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
10%
KEV
Not listed

Published

August 13, 2026

Last Modified

August 13, 2026

Advisory Details (1)

Auto-updated Aug 13, 2026
Patch available. Sources: github.
github Patch Available

Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass in `@backstage/plugin-auth-backend` · Advisory · backstage/backstage · GitHub

https://github.com/backstage/backstage/security/advisories/GHSA-38hq-7x33-php4

Vendor Advisories for CVE-2026-73563(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
@backstage/plugin-auth-backend—0.29.2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 28× 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.

  1. 2026-08-26 20:52 UTCEG score recompute
  2. 2026-08-26 14:47 UTCEPSS rescore
  3. 2026-08-25 22:13 UTCEG score recompute
  4. 2026-08-25 13:49 UTCEPSS rescore
  5. 2026-08-24 23:50 UTCEG score recompute
  6. 2026-08-23 03:06 UTCEG score recompute
  7. 2026-08-23 00:19 UTCEPSS rescore
  8. 2026-08-22 04:44 UTCEG score recompute
  9. 2026-08-21 23:49 UTCEPSS rescore
  10. 2026-08-21 06:22 UTCEG score recompute
  11. 2026-08-20 22:56 UTCEPSS rescore
  12. 2026-08-20 08:00 UTCEG score recompute
  13. 2026-08-19 17:04 UTCEPSS rescore
  14. 2026-08-19 09:38 UTCEG score recompute
  15. 2026-08-18 13:49 UTCEPSS rescore
  16. 2026-08-18 13:49 UTCEPSS rescore
  17. 2026-08-18 11:14 UTCEG score recompute
  18. 2026-08-17 13:47 UTCEPSS rescore
  19. 2026-08-17 12:51 UTCEG score recompute
  20. 2026-08-16 14:56 UTCEPSS rescore
  21. 2026-08-16 14:56 UTCEPSS rescore
  22. 2026-08-16 14:29 UTCEG score recompute
  23. 2026-08-16 02:15 UTCEPSS rescore
  24. 2026-08-15 16:07 UTCEG score recompute
  25. 2026-08-15 01:31 UTCEPSS rescore
Show 3 more
  1. 2026-08-13 18:18 UTCEG score recompute
  2. 2026-08-13 17:47 UTCEG score recompute
  3. 2026-08-13 17:46 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-73563?
CVE-2026-73563 is a medium vulnerability published on August 13, 2026. Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob matching for…
When was CVE-2026-73563 disclosed?
CVE-2026-73563 was first published in the National Vulnerability Database on August 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-73563 actively exploited?
CVE-2026-73563 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 90.0% of all scored CVEs.
What is the CVSS score of CVE-2026-73563?
CVE-2026-73563 has a CVSS v3 base score of 4.7 (NVD).
How do I remediate CVE-2026-73563?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-73563, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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