Open Redirect in SSO Authentication Flow Steals Session Tokens

SigNoz through 0.133.0 contains an open redirect vulnerability in the SSO authentication flow that allows unauthenticated attackers to steal session tokens from any user on instances configured with Google OAuth, SAML, or OIDC. Attackers can call the unauthenticated sessions context endpoint with a ref parameter pointing to an attacker-controlled host, deliver the resulting crafted login URL to a victim, and receive the victim's access and refresh tokens when they complete SSO authentication.

Casky was already ahead

This CVE exploits attack patterns that Casky's 446matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

SigNoz versions through 0.133.0 suffer from a critical open redirect vulnerability in their SSO authentication implementation that affects instances using Google OAuth, SAML, or OIDC. The vulnerability allows unauthenticated attackers to manipulate the `ref` parameter in the sessions context endpoint, redirecting users to attacker-controlled hosts during the login process. When victims complete SSO authentication, their access and refresh tokens are captured by the attacker, granting complete account compromise. This impacts any organization using SigNoz for observability with federated identity providers, as the attack requires no prior authentication and can be weaponized through phishing campaigns delivering crafted login URLs.

Casky's 446 matching security skills leverage Claude's extended reasoning to detect this attack pattern across multiple MITRE ATT&CK techniques: Initial Access (TA0001) through phishing with malicious login links, Credential Access (TA0043) via token interception at the redirect endpoint, and Execution (TA0002) of post-compromise actions once tokens are obtained. Practitioners using Casky would observe findings highlighting suspicious redirect parameters in authentication logs, token exfiltration to external domains during SSO flows, and anomalous session creation from unexpected IP addresses. The platform would flag the combination of unauthenticated access to session endpoints paired with external domain redirects—a clear indicator of open redirect exploitation—enabling defenders to identify and block exploitation attempts before token theft occurs.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

446 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-63094.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043 TA0002

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