Security Affairs newsletter Round 529 by Pierluigi Paganini

CVE-2023-28771 is an unauthenticated OS command injection flaw (CWE-78) in Zyxel firewall firmware, caused by improper error message handling in the IKE packet decoder. A remote attacker triggers it by sending crafted packets to an affected device, with no credentials or user interaction required (CVSS 3.1: 9.8, network vector, low complexity). Successful exploitation lets the attacker execute operating-system commands on the firewall, which typically means full device compromise of these perimeter/VPN gateway appliances. Organizations running Zyxel ZyWALL/USG, VPN, USG FLEX, or ATP series firewalls on the affected firmware ranges are exposed, especially where IKE/VPN traffic is reachable from the internet. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV on 2023-05-31, carries a 99.3% EPSS score (100th percentile), is reportedly used by DDoS botnets, and was reportedly exploited in the May 2023 coordinated attacks against nearly two dozen Danish energy companies.

Do: Apply Zyxel's patched firmware to all affected devices per the vendor advisory - releases newer than 4.73 for ZyWALL/USG and newer than 5.35 for ATP, USG FLEX, and VPN series - prioritizing internet-facing and VPN gateway appliances, as this is a KEV required-action vulnerability. Where immediate patching is not possible, restrict IKE traffic (UDP 500/4500) to trusted peers or disable unneeded IPsec VPN termination. After patching, review device logs and configurations for signs of command execution or unexpected changes, given confirmed botnet and targeted-attack use.

CVE-2025-23121 is a code-injection vulnerability (CWE-94) in Veeam Backup & Replication that allows an authenticated domain user to execute arbitrary code on the Backup Server over the network. An attacker triggers it by sending a crafted request to the backup server's network-facing components using valid, low-privileged domain credentials, with no user interaction required. Successful exploitation yields full remote code execution with high impact on confidentiality, integrity and availability of the backup server (CVSS 3.1: 8.8 per the vector provided, though some coverage lists a 9.9 score). Any organization running Veeam Backup & Replication is affected, particularly environments where many or low-privilege domain accounts can reach the backup server. As of this writing it is not in CISA KEV and no public PoC is known, but the EPSS of 22.2% (98th percentile) indicates an elevated probability of exploitation within the next 30 days, and Veeam has shipped a fix.

Do: Upgrade Veeam Backup & Replication to the latest patched release per Veeam's security advisory for CVE-2025-23121. In the meantime, restrict which domain accounts can authenticate to the Backup Server, ensure the server is not exposed to the public internet, and audit for unusual process execution or network connections from backup infrastructure. Given the high EPSS score, prioritize patching and monitor Veeam/Kev feeds for signs of in-the-wild exploitation.

Langflow, an open-source visual framework for building LLM and agentic AI applications, contains a missing authentication flaw (CWE-306) in its /api/v1/validate/code endpoint. A remote attacker with network reachability to the endpoint can send crafted HTTP requests without any credentials, causing arbitrary code execution on the server. Successful exploitation yields code execution under the application's privileges, enabling data theft, backdoor installation, and, per CISA, ransomware deployment. Any running Langflow instance is affected; the tool is typically self-hosted by development teams building AI workflows, so real-world exposure depends on whether each instance is reachable from untrusted networks. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV catalog on 2025-05-05 with known ransomware use, EPSS assigns a 100% probability of exploitation within 30 days (100th percentile), and a public PoC is available.

Do: Upgrade Langflow to the latest patched release identified in the vendor's advisory; federal agencies must apply mitigations per vendor instructions under BOD 22-01 or discontinue use if mitigations are unavailable. Until patched, restrict network access to the /api/v1/validate/code endpoint via reverse-proxy authentication, firewall rules, or VPN placement, and avoid exposing Langflow directly to the internet. Because ransomware use is confirmed, review access and process-execution logs for signs of prior compromise.