CVE-2026-92161: FriendsOfFlarum OAuth: Unauthenticated account takeover via unverified email trust in Discord OAuth provider

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 0.3%, percentile 18: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 18% of all scored CVEs (low). 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 fof/oauth (Composer (PHP)) < 1.7.4, fixed in 1.7.4; fof/oauth (Composer (PHP)) >= 2.0.0-beta.1, < 2.0.0-beta.4, fixed in 2.0.0-beta.4. Check your lockfile, including transitive dependencies.

What it is

FriendsOfFlarum OAuth allows users to log in to Flarum with GitHub, Twitter, Facebook, and other providers. Prior to 1.7.4 and 2.0.0-beta.4, the Discord OAuth provider does not check the verified field returned for an OAuth email before passing the address to Flarum core as trusted through provideTrustedEmail(). When Discord sign-in is enabled, an unauthenticated attacker who knows the email address of a Flarum user can configure a Discord account with that unverified address and a verified phone number, then sign in to cause Flarum to match the trusted address, link the attacker-controlled Discord identity to the existing user, and authenticate as the victim without a password or victim interaction. Exploitation requires that the victim's email address is not already associated with a Discord account, and it can compromise administrator accounts. Other bundled providers were not confirmed to be practically exploitable by this method because their relevant authentication flows return only verified or confirmed email addresses. This issue is fixed in versions 1.7.4 and 2.0.0-beta.4.

From the GitHub advisory

Impact

An unauthenticated account takeover vulnerability exists in fof/oauth when the Discord OAuth provider is enabled.

Discord allows an account to use an unverified email address when its phone number has been verified. During OAuth authentication, Discord may return that email address with "verified": false.

Affected versions of fof/oauth did not validate this flag and passed the email address to Flarum core as trusted via provideTrustedEmail(). Flarum core could then match the trusted email address to an existing user, link the attacker-controlled Discord identity to that user, and authenticate the attacker as the victim.

An attacker who knows a user's email address can therefore take over the corresponding Flarum account without knowing its password or requiring any interaction from the victim. This includes administrator accounts.

Weakness type: CWE-345.

Product: fof/oauth (Composer (PHP)) · Assigned by: GitHub_M · Published: 2026-09-25

Affected and fixed versions

Severity scores

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

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): 0.27% probability of exploitation activity in the next 30 days; percentile 18.

Timeline

• 2026-09-25 — CVE record published by GitHub_M
• 2026-09-25 — GitHub-reviewed advisory GHSA-g7vj-c29h-3h5m published (critical)
• 2026-09-29 — 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-g7vj-c29h-3h5m github.com
2. CVE.org record CVE-2026-92161 cve.org
3. NVD entry CVE-2026-92161 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest