Description

An issue in wpa_supplicant all versions before v.2.12 allows a local attacker to bypass proper network context and AKMP matching for PMKSA caching via missing validation in the driver based PMKSA selection path in wpa.c

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-09-11T18:16:58.120Z",
  "pubdate": "2026-09-11T18:16:58.120Z",
  "executiveSummary": "A security vulnerability exists in wpa_supplicant affecting all versions prior to v.2.12. The flaw resides within the driver-based PMKSA (Pairwise Master Key Security Association) selection path, specifically located in wpa.c.\nThe vulnerability is characterized as a logic error where the system fails to perform essential validation checks on network context and AKMP (Authentication and Key Management Protocol) matching. This oversight allows a local attacker to influence the PMKSA caching mechanism improperly.\nThe primary impact involves the bypassing of security constraints intended to restrict network access based on authenticated contexts. By forcing the system to utilize an incorrect or unauthorized PMKSA, an attacker can potentially authenticate to a network using cached credentials that do not match the target network's specific security parameters.\nThis vulnerability requires local access to the system to exploit. It represents a significant risk in environments relying on fast-roaming or 802.11r/i features where cached PMKSAs are utilized to streamline re-authentication. Successful exploitation results in unauthorized network association, undermining the integrity of the WPA handshake process.",
  "technicalDetails": "The root cause of the vulnerability is located in the wpa.c file within the wpa_supplicant source code. Specifically, the implementation of the driver-based PMKSA selection path lacks robust validation logic required to ensure that a selected PMKSA strictly adheres to the established network context and the required AKMP suite for the target network.\nWhen wpa_supplicant initiates an association, it may attempt to leverage existing PMKSA entries stored in the cache to accelerate the authentication handshake. Under normal operating conditions, the supplicant is responsible for verifying that the chosen PMKSA is compatible with the current network's BSSID, SSID, and the negotiated AKMP suite. The vulnerability arises because the selection logic in the driver-based path fails to enforce these checks before passing the PMKSA candidate to the driver/firmware.\nAn attacker with local access can manipulate the supplicant's state to influence which PMKSA is selected. By exploiting the missing validation, the attacker forces the supplicant to present a cached PMKSA that was originally generated for a different network or an incompatible security configuration. Because the supplicant does not verify that the AKMP and context match the current target, it incorrectly assumes the PMKSA is valid for the current association attempt.\nThe attack flow follows these steps: First, the attacker ensures a PMKSA is stored in the cache from a previous association with an arbitrary, perhaps attacker-controlled or misconfigured, network. Second, the attacker triggers an association attempt with a target network that requires different security parameters or a different AKMP suite. Third, due to the missing validation in wpa.c, the driver-based path selects the previously cached, incompatible PMKSA. Finally, the supplicant proceeds with the association process using the unauthorized PMKSA, potentially bypassing the intended security policy or allowing the attacker to masquerade as an authenticated entity in a context that should have been prohibited.\nThis behavior undermines the security assertions of the WPA handshake, as the PMKSA acts as the derivative key material for subsequent traffic encryption. If the selection logic is subverted, the cryptographic binding between the supplicant and the access point is weakened, enabling unauthorized access to the network infrastructure."
}