Description

Insufficiently protected credentials in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.3",
  "pubDate": "2026-08-11T17:18:39.203Z",
  "pubdate": "2026-08-11T17:18:39.203Z",
  "executiveSummary": "This vulnerability involves insufficiently protected credentials within Microsoft Office Outlook, enabling an unauthorized remote attacker to execute spoofing attacks over a network.\nThe primary impact of this security flaw is the compromise of message integrity and origin authenticity, which can facilitate phishing campaigns, credential harvesting, or deceptive communications appearing as legitimate entities.\nThe affected product is Microsoft Office Outlook.\nRisk implications are severe due to the widespread enterprise deployment of the client, potentially leading to unauthorized access, privilege escalation, or lateral movement if exploited successfully.\nAttacker capabilities include network-based interception, manipulation, or fabrication of message attributes by leveraging weak credential handling mechanisms.\nExploitation requirements typically necessitate network access and the ability to interact with vulnerable Outlook communication channels or intercept traffic streams.",
  "technicalDetails": "The root cause of the vulnerability stems from inadequate protection, storage, or transmission mechanisms for credentials within Microsoft Office Outlook.\nThe vulnerable component resides in the credential management and authentication subsystems of Microsoft Office Outlook, specifically where identity verification and session tokens or credentials are handled.\nAttackers exploit this flaw by leveraging the inadequate protection of credentials to intercept, forge, or spoof authentication data and protocol exchanges over the network.\nThe step-by-step attack flow typically begins with an unauthorized threat actor positioning themselves within network reach or establishing a connection capable of interacting with the target Microsoft Office Outlook instance.\nThe attacker observes or intercepts insufficiently protected credential artifacts or authentication handshakes processed by the application.\nBy leveraging these exposed or weakly protected credentials, the attacker crafts malicious requests or manipulates protocol parameters to spoof legitimate user actions or communications.\nNetwork exposure is a prerequisite, as the attack vector requires network connectivity to target the client application's communication interfaces.\nAuthentication and privilege requirements for the initial exploitation phase are minimal from an external perspective, allowing unauthenticated or low-privileged network attackers to leverage the cryptographic or design weaknesses in credential handling.\nPost-exploitation impact includes unauthorized message spoofing, session hijacking, or unauthorized access to sensitive messaging infrastructure and downstream services relying on Outlook-based authentication tokens."
}