CVE-2024-39912

Description

### Summary The ProfileBasedRequestOptionsBuilder method returns allowedCredentials without any credentials if no username was found. ### Details When WebAuthn is used as the first or only authentication method, an attacker can enumerate usernames based on the absence of the `allowedCredentials` property in the assertion options response. This allows enumeration of valid or invalid usernames. #### Proposal how to resolve it: ``` return $this->publicKeyCredentialRequestOptionsFactory->create( $this->profile, count($allowedCredentials) <= 0 ? self::getRandomCredentials(): $allowedCredentials, $optionsRequest->userVerification, $extensions ); private static function getRandomCredentials(): array { $credentialSources = []; for ($i = 0; $i <= rand(0,1); $i++) { $credentialSources[] = new PublicKeyCredentialSource( random_bytes(32), "public-key", [], "basic", new EmptyTrustPath(), Uuid::v7(), random_bytes(77), Uuid::v7()->__toString(), rand(0, 6000), null ); } return array_map( static fn (PublicKeyCredentialSource $credential): PublicKeyCredentialDescriptor => $credential->getPublicKeyCredentialDescriptor(), $credentialSources ); } ``` ### PoC curl https://example.com/assertion/options \ -H 'content-type: application/json' \ --data-raw '{"username":"NotMeRandomUsername123"}' ### Impact By knowing which usernames are valid, attackers can focus their efforts on a smaller set of potential targets, increasing the efficiency and likelihood of successful attacks.

How to fix CVE-2024-39912

To remediate CVE-2024-39912, upgrade the affected package to a fixed version below.

• —upgrade to 4.9.0 or later
• —upgrade to 4.9.0 or later

Is CVE-2024-39912 being exploited?

Low — EPSS is 0.4%, meaning exploitation activity has not been observed at scale.