CVE-2026-54072: Authorizer: Unvalidated redirect_uri in /authorize leaks OAuth2 tokens to attacker-controlled URL

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.5%, percentile 39: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 39% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
• Only applies if your dependency tree includes github.com/authorizerdev/authorizer (Go) < 0.0.0-20260409051328-bd3f5baf6d3d, fixed in 0.0.0-20260409051328-bd3f5baf6d3d. Check your lockfile, including transitive dependencies.

What it is

Authorizer is an open-source, self-hostable authentication and authorization server. Prior to version 2.2.1, the /authorize endpoint accepts any redirecturi without validating it against AllowedOrigins. When responsetype=token or responsetype=idtoken, the server appends accesstoken, idtoken, and refreshtoken as query parameters and issues a 302 redirect to the attacker-supplied URL. An unauthenticated attacker can obtain the required clientid from the public /graphql?query={meta{clientid}} endpoint. A partial fix was applied in v2.0.1 to other handlers (oauthlogin, verifyemail, magiclinklogin, forgotpassword, invitemembers, oauthcallback) but /authorize was not included. Version 2.2.1 contains a more complete fix.

From the GitHub advisory

Summary

The /authorize endpoint accepts any redirecturi without validating it against AllowedOrigins. When responsetype=token or responsetype=idtoken, the server appends accesstoken, idtoken, and refreshtoken as query parameters and issues a 302 redirect to the attacker-supplied URL. An unauthenticated attacker can obtain the required clientid from the public /graphql?query={meta{clientid}} endpoint.

Partial fix was applied in v2.0.1 to other handlers (oauthlogin, verifyemail, magiclinklogin, forgotpassword, invitemembers, oauthcallback) but /authorize was not included.

Vulnerable Code

internal/httphandlers/authorize.go:

Weakness type: CWE-601.

Product: github.com/authorizerdev/authorizer (Go) · Assigned by: GitHub_M · Published: 2026-09-11

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.46% probability of exploitation activity in the next 30 days; percentile 39.

Timeline

• 2026-07-10 — GitHub-reviewed advisory GHSA-h29v-hj44-q8cv published (critical)
• 2026-09-11 — CVE record published by GitHub_M
• 2026-09-15 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-h29v-hj44-q8cv github.com
2. CVE.org record CVE-2026-54072 cve.org
3. NVD entry CVE-2026-54072 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com

Critical Go advisories · Today’s Security Digest