Description

openssl_encrypt before 1.4.0 contains an authentication bypass vulnerability in the verify_api_token function that accepts any non-empty Bearer token string without validation. Attackers can upload arbitrary public keys, enumerate all keys, and revoke keys belonging to any user by providing any Bearer token in the Authorization header.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-08-17T11:16:44.523Z",
  "pubdate": "2026-08-17T11:16:44.523Z",
  "executiveSummary": "An authentication bypass vulnerability exists within openssl_encrypt prior to version 1.4.0, specifically residing in the verify_api_token function. This flaw allows unauthorized actors to circumvent access controls entirely by supplying any arbitrary, non-empty Bearer token string within the HTTP Authorization header, as the underlying validation logic fails to cryptographically verify or authenticate the provided token against legitimate credentials.\nThe impact of this security deficiency is severe, enabling remote attackers to execute unauthorized administrative and state-changing actions across affected systems. Successful exploitation grants malicious actors the capability to upload arbitrary public keys, systematically enumerate all registered keys within the system, and arbitrarily revoke cryptographic keys belonging to any user without possessing valid authorization credentials.\nThis vulnerability directly affects implementations of openssl_encrypt prior to version 1.4.0 utilizing the vulnerable API token verification mechanism. The risk implications include complete compromise of key management subsystems, unauthorized data exposure through key enumeration, and denial of service via unauthorized key revocation.\nAttacker capabilities require network access to the API endpoints utilizing the vulnerable verify_api_token function. Exploitation requirements are minimal, demanding only the ability to craft HTTP requests containing a malformed or arbitrary non-empty Bearer token string in the Authorization header to successfully bypass authentication checks.",
  "technicalDetails": "The root cause of the vulnerability stems from improper input validation and missing cryptographic verification within the verify_api_token function of openssl_encrypt before version 1.4.0. Instead of performing a robust cryptographic signature check, session validation, or database lookup against issued tokens, the function evaluates the presence of the Authorization header and accepts any string provided as a Bearer token as long as it is non-empty. This absence of strict token parsing and validation logic creates a critical authentication bypass condition.\nThe vulnerable component is the verify_api_token function handling API request authentication across affected versions prior to 1.4.0. The authentication requirements are effectively nullified for attackers who supply the malformed header, while privilege requirements are bypassed entirely because the application treats the unvalidated token as proof of valid session authentication.\nThe attack flow proceeds as follows: First, an unauthenticated attacker crafts an HTTP request targeting functionality protected by the verify_api_token mechanism, such as key upload, key enumeration, or key revocation endpoints. Second, the attacker inserts an arbitrary, non-empty string prefixed with the Bearer scheme into the Authorization header of the outbound HTTP request. Third, the application intercepts the request and invokes the verify_api_token function to authenticate the sender. Fourth, the vulnerable function evaluates the token string, checks only that the string contains non-empty characters, and returns a positive validation status to the calling application without performing actual token validation.\nFollowing the successful authentication bypass, the attacker's request is processed with elevated privileges implicitly granted by the flawed validation routine. The payload behavior allows the attacker to execute unauthorized administrative routines, specifically facilitating the upload of arbitrary public keys into the system keystore, execution of enumeration queries to retrieve all registered keys, and invocation of revocation commands targeting cryptographic keys owned by arbitrary users. The post-exploitation impact includes persistent unauthorized manipulation of cryptographic assets, potential man-in-the-middle positioning via unauthorized public key injection, and catastrophic disruption of legitimate user operations through malicious key revocations."
}