Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.28% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-73563High confidence
Backstage: Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass in `@backstage/plugin-auth-backend`
backstage · backstage
Official source article: GitHub GHSA-38HQ-7X33-PHP4 ↗. Check the applicable product and release in the original source.
4.7MediumCVSS 3.1
Scheduled
Patch availableMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs backstage backstage and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Open-source package ranges1 source-attributed range
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| npm@backstage/plugin-auth-backend | <= 0.29.1 | 0.29.2 | GitHub advisory ↗upstream repository advisory · 13 Aug 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-73563 · CSAF 2.0 · revision 3 · finalRed Hat Product Security@backstage/plugin-auth-backend: Backstage: Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass
The vendor explicitly identifies these products or versions as containing the fix.
- registry.redhat.io/ansible-automation-platform/automation-portal@sha256:7145c54b94927bc64e9def7a47cb43b7706ee21d41f8dd97a08ea8ff1fcad65e_amd64 as a component of Red Hat Ansible Automation Platform 2.1
- registry.redhat.io/ansible-automation-platform/automation-portal@sha256:60327d55eb419b955cea0d2d0693d820fe31040a006a38146aa524240528afff_amd64 as a component of Red Hat Ansible Automation Platform 2.2
- Summary
- A flaw was found in the `@backstage/plugin-auth-backend` component of Backstage. This vulnerability allows an unauthenticated remote attacker to bypass the `redirect_uri` allowlist in the experimental dynamic client registration feature. By crafting a malicious redirect Uniform Resource Identifier (URI) with a trusted hostname suffix, an attacker can receive an OAuth authorization code, potentially leading to an account takeover. This issue affects deployments that have enabled the experimental features and configured custom wildcard-hostname or protocol-less patterns.
- Remediation
- For more about Ansible plugins for Red Hat Developer Hub, see References links
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available01
What, why and how
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.
What
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.
Why
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
How
An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
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.
Why
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
How
An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → URL Redirection to Untrusted Site ('Open Redirect') → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Required interaction required
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Changed: exploitation can affect a different security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-601 ↗
CWE-601: URL Redirection to Untrusted Site ('Open Redirect'). The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:NCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SChangedScope: The attack can affect a component governed by a different security authority.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- backstage: < 0.29.2
- Fixed
- registry.redhat.io/ansible-automation-platform/automation-portal@sha256:7145c54b94927bc64e9def7a47cb43b7706ee21d41f8dd97a08ea8ff1fcad65e_amd64 as a component of Red Hat Ansible Automation Platform 2.1
- registry.redhat.io/ansible-automation-platform/automation-portal@sha256:60327d55eb419b955cea0d2d0693d820fe31040a006a38146aa524240528afff_amd64 as a component of Red Hat Ansible Automation Platform 2.2
- Action
- For more about Ansible plugins for Red Hat Developer Hub, see References links
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 13 Aug 2026 · Last source change 13 Aug 2026, 18:07 UTC · CWE-601 · URL Redirection to Untrusted Site ('Open Redirect')
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-58177
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- backstage: < 0.29.2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- backstage: < 0.29.2 · Fixed: For more about Ansible plugins for Red Hat Developer Hub, see References links
- Remediation statusRemediation status changed from Awaiting fix to Patch available.Red Hat Product Security ↗
- Before
- Awaiting fix
- After
- Patch available
- Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-73563 to remediation: access.redhat.com/CVE-2026-73563.Red Hat Product Security ↗
- Before
- remediation: access.redhat.com/CVE-2026-73563
- After
- remediation: access.redhat.com/CVE-2026-73563
- Remediation statusRemediation status changed from Mitigation available to Patch available.Red Hat Product Security ↗
- Before
- Mitigation available
- After
- Patch available
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- ansible-automation-platform/automation-portal as a component of Self-service automation portal 2
- After
- Fixed: registry.redhat.io/ansible-automation-platform/automation-portal@sha256:7145c54b94927bc64e9def7a47cb43b7706ee21d41f8dd97a08ea8ff1fcad65e_amd64 as a component of Red Hat Ansible Automation Platform 2.1; registry.redhat.io/ansible-automation-platform/automation-portal@sha256:60327d55eb419b955cea0d2d0693d820fe31040a006a38146aa524240528afff_amd64 as a component of Red Hat Ansible Automation Platform 2.2
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- rhdh/rhdh-hub-rhel9 as a component of Red Hat Developer Hub; ansible-automation-platform/automation-portal as a component of Self-service automation portal 2
- After
- ansible-automation-platform/automation-portal as a component of Self-service automation portal 2
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- < 0.29.2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- backstage: < 0.29.2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
CVE published
Fixed release recorded from official guidance
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.