Hackers exploit vulnerabilities in IBM Langflow N-able N-central and Apache Tomcat

Summary

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued an urgent directive for federal agencies to mitigate three high-impact vulnerabilities currently being exploited in the wild. The flaws affect IBM Langflow, N-able N-central, and Apache Tomcat, providing attackers with paths to remote code execution and administrative account hijacking.

Federal agencies have been given a deadline of August 7 to apply available mitigations. CISA has added all three vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog following evidence of active exploitation.

Technical Details

IBM Langflow RCE

The vulnerability in IBM's Langflow visual framework, tracked as CVE-2026-9198, allows unauthenticated attackers to execute code remotely on default deployments. The attack involves chaining two distinct API endpoints: an unauthenticated endpoint that issues superuser bearer tokens to any network caller, and a code validation endpoint that executes arbitrary Python code. An attacker can obtain a superuser token via the auto-login endpoint and then submit malicious code through the validation endpoint.

N-able N-central Authentication Bypass

N-able's remote monitoring and management platform, N-central, is subject to an authentication bypass vulnerability tracked as CVE-2026-18556. Threat actors have used this zero-day flaw to gain administrative access and connect to managed systems. While a fix was previously issued, it was found to be insufficient; attackers subsequently bypassed the initial patch. A new emergency hotfix has been released to address this bypass.

Apache Tomcat EncryptInterceptor Bypass

The vulnerability in Apache Tomcat, tracked as CVE-2026-34486, stems from an incomplete fix for a previous issue (CVE-2026-29146). The flaw involves the EncryptInterceptor, an optional channel interceptor used to encrypt messages between nodes in a cluster.

The original patch moved a single line of code, which changed the encryption layer from fail-closed to fail-open. This allows attackers to bypass decryption; instead of rejecting unauthorized messages, the system forwards attacker-controlled code up the interceptor chain unmodified, leading to unauthenticated remote code execution on cluster members. Researchers have observed Chinese-speaking threat actors attempting to exploit this flaw to plant reverse shells on Apache Tomcat servers.

Affected Products and Fixed Versions

Defender Guidance

Prioritize N-central Updates N-able customers must install the emergency hotfix immediately. Because the initial patch for the authentication bypass was bypassed by threat actors, standard update procedures may not be sufficient without this specific hotfix.

Secure Langflow Deployments For those running IBM Langflow, ensure you are running version 1.10.1 or later. Default deployments are particularly vulnerable to the token-issuing endpoint flaw.

Update Apache Tomcat Clusters If using EncryptInterceptor in a cluster configuration, upgrade to the latest versions (11.0.21, 10.1.54, or 9.0.117) to close the fail-open path that allows unauthenticated code execution.

Monitor for Indicators of Compromise Watch for unauthorized administrative access in N-central and unexpected Python code execution in Langflow environments. For Apache Tomcat, monitor for reverse shell activity following failed decryption attempts.