CVE-2024-28054 is a vulnerability in Amavis, an open-source content filter used primarily for email scanning and malware detection. The flaw stems from an interpretation conflict related to MIME message parsing, specifically when multiple boundary parameters are present in a MIME email message. Amavis relies on the MIME-tools library to parse these messages, but due to inconsistent interpretation of these boundaries relative to some mail user agents, Amavis may incorrectly process the MIME structure. This leads to a failure in properly detecting banned files or malware embedded within email attachments. The vulnerability affects versions of Amavis before 2.12.3 and 2.13.x before 2.13.1. The CVSS v3.1 score is 7.4, indicating high severity, with the vector showing network attack vector (AV:N), high attack complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality and integrity (C:H/I:H), but no impact on availability (A:N). Exploiting this vulnerability could allow attackers to bypass email security controls, delivering malicious payloads that evade detection. Although no exploits are known in the wild yet, the vulnerability poses a significant risk to organizations relying on Amavis for email filtering. The CWE-436 classification refers to 'Interpretation Conflict,' highlighting the root cause in MIME boundary parsing inconsistencies. The lack of patch links suggests that users should monitor official Amavis releases closely and apply updates promptly once available.

For European organizations, this vulnerability could lead to the bypass of email security defenses, allowing malware or banned content to enter corporate networks undetected. This can compromise sensitive data confidentiality and integrity, especially in sectors heavily reliant on email communication such as finance, healthcare, government, and critical infrastructure. The failure to detect malicious attachments increases the risk of ransomware, data breaches, and advanced persistent threats. Since Amavis is widely used in open-source mail filtering stacks, organizations using it as part of their email security infrastructure are at risk. The high attack complexity reduces the likelihood of widespread automated exploitation, but targeted attacks against high-value European entities remain a concern. The absence of known exploits in the wild currently limits immediate impact, but the vulnerability's nature makes it a prime candidate for future exploitation once weaponized. Organizations failing to patch or mitigate this vulnerability may face regulatory and compliance challenges under GDPR and other data protection laws if breaches occur.

European organizations should immediately inventory their email filtering infrastructure to identify Amavis deployments and their versions. Applying official patches from Amavis as soon as they are released is critical. In the interim, organizations can implement additional layers of email security, such as sandboxing attachments, employing alternative malware scanning engines, or deploying heuristic and behavior-based detection systems to complement Amavis. Configuring strict email attachment policies and increasing monitoring of email traffic for anomalous patterns can help detect potential bypass attempts. Network segmentation and limiting the impact of compromised email accounts will reduce potential damage. Regularly updating MIME-tools and related dependencies may also help, although the primary fix must come from Amavis updates. Security teams should also educate users about phishing and suspicious attachments, as user awareness remains a key defense layer. Finally, organizations should monitor threat intelligence feeds for any emerging exploit attempts targeting this vulnerability.