CVE-2026-29792: Feathers has an OAuth Callback Account Takeover issue

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.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.7%, percentile 51: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 51% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes @feathersjs/authentication-oauth (npm) >= 5.0.0, <= 5.0.41, fixed in 5.0.42. Check your lockfile, including transitive dependencies.

What it is

Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. From 5.0.0 to before 5.0.42, an unauthenticated attacker can send a crafted GET request directly to /oauth/:provider/callback with a forged profile in the query string. The OAuth service's authentication payload has a fallback chain that reaches params.query (the raw request query) when Grant's session/state responses are empty. Since the attacker never initiated an OAuth authorize flow, Grant has no session to work with and produces no response, so the fallback fires. The forged profile then drives entity lookup and JWT minting. The attacker gets a valid access token for an existing user without ever contacting the OAuth provider. This vulnerability is fixed in 5.0.42.

From the GitHub advisory

An unauthenticated attacker can send a crafted GET request directly to /oauth/:provider/callback with a forged profile in the query string. The OAuth service's authentication payload has a fallback chain that reaches params.query (the raw request query) when Grant's session/state responses are empty. Since the attacker never initiated an OAuth authorize flow, Grant has no session to work with and produces no response, so the fallback fires. The forged profile then drives entity lookup and JWT minting. The attacker gets a valid access token for an existing user without ever contacting the OAuth provider. Critical (CVSS 9.8)

Weakness type: CWE-287.

Product: @feathersjs/authentication-oauth (npm) · Assigned by: GitHub_M · Published: 2026-03-10

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

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 none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.65% probability of exploitation activity in the next 30 days; percentile 51.

Timeline

• 2026-03-10 — CVE record published by GitHub_M
• 2026-03-10 — GitHub-reviewed advisory GHSA-wg9x-qfgw-pxhj published (critical)
• 2026-03-11 — 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-wg9x-qfgw-pxhj github.com
2. CVE.org record CVE-2026-29792 cve.org
3. NVD entry CVE-2026-29792 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com

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