The US Cybersecurity and Infrastructure Security Agency (CISA) issued a fresh warning: threat actors are actively exploiting vulnerabilities affecting Langflow OSS, N-able N-central, and Apache Tomcat. These issues are now tracked in CISA’s Known Exploited Vulnerabilities (KEV) catalog, underscoring that real-world attacks are underway—not just theoretical risk.
Because exploited systems can quickly turn into a foothold for larger intrusions, CISA is urging organizations to patch all three vulnerabilities by August 7. Below is what is known about each flaw, the potential impact, and what defenders should do next.
Why CISA’s KEV listing matters
CISA adds vulnerabilities to the KEV catalog when there is evidence that they are being exploited in the wild. That designation is more than a status update: it typically signals that attackers have reliable, repeatable techniques and that delays in remediation increase exposure.
In this case, CISA tied the warning to three separate products—Langflow N-central Tomcat—each with different exploitation paths and severity levels. The shared theme is straightforward: patching needs to happen quickly and methodically.
Langflow OSS: chained APIs can lead to remote code execution
The first issue involves IBM Langflow OSS. The vulnerability is tracked as CVE-2026-9198, with a CVSS score of 9.8, making it one of the most critical items in the alert.
IBM said the bug enables unauthenticated attackers to chain two API endpoints to achieve remote code execution. In other words, an attacker does not need valid login credentials to start the process.
How the attack chain works
According to IBM’s description, the weakness combines two distinct problems:
- An unauthenticated endpoint that could issue superuser bearer tokens to any network caller.
- A code validation endpoint capable of executing arbitrary Python code.
IBM warned that an attacker could first obtain a superuser token through an auto-login-related mechanism, then use that token to submit malicious code to the validation endpoint.
Patch timeline and affected deployments
The flaw was disclosed on July 17, and IBM released patches at that time. IBM also warned that all default deployments are affected, with remediation available in Langflow OSS version 1.10.1.
After public disclosure, proof-of-concept code reportedly appeared about a week later, increasing the odds that exploit attempts would accelerate. CISA then added the CVE to its KEV catalog on August 4.
N-able N-central: authentication bypass enables administrative access
The second vulnerability targets N-able N-central. CISA lists it as exploited and assigns it CVE-2026-18556 with a CVSS score of 7.4.
This issue is described as an authentication bypass. In practice, that means attackers can bypass authentication controls and reach privileged functionality without proper credentials.
Zero-day behavior and attacker goals
Per N-able, threat actors exploited the vulnerability as a zero-day to gain administrative access. They then used that access to connect to systems managed through the platform’s remote monitoring and management (RMM) capabilities.
Because RMM platforms often manage large fleets of devices, administrative access can have outsized consequences—ranging from further compromise to persistent control.
Initial fix gaps and follow-up hotfix
N-able stated that the first fix for CVE-2026-18556 was incomplete, and attackers bypassed it. As exploitation activity increased toward the end of July, N-able issued a hotfix that produced a new tracking identifier: CVE-2026-18577.
CISA has now included both CVE-2026-18556 and CVE-2026-18577 in the KEV list. For defenders, that means patching should not stop at the first update—verify that systems are at the correct, bypass-resistant version.
Apache Tomcat: EncryptInterceptor bypass can open remote code execution paths
The third vulnerability affects Apache Tomcat, tracked as CVE-2026-34486 with a CVSS score of 7.5. CISA added this issue to the KEV catalog on Tuesday.
Unlike the Langflow issue, this Tomcat bug is tied to a specific component: an EncryptInterceptor bypass. The vulnerability relates to message encryption behavior in clustered environments.
What Tomcat’s EncryptInterceptor does
EncryptInterceptor is an optional channel interceptor that encrypts messages transmitted between nodes in Tomcat clusters. When configured, only messages encrypted with a shared key should be decrypted and passed onward to the deserialization layer.
However, the bypass changed how failures are handled. As StrigaAI explained, the fix involved moving a line of code, and that change shifted the encryption layer from fail-closed to fail-open.
That combination—when implemented incorrectly—can create a direct pathway to unauthenticated remote code execution on each cluster member.
Evidence of exploitation in separate reports
Security reporting in the period after patching suggested the issue had already been leveraged by advanced attackers. SOCRadar warned that CVE-2026-34486 was exploited in activity involving the Snowlight malware family. Separately, Palo Alto Networks observed exploitation by Chinese hackers in an AI-enabled autonomous hacking campaign.
While those reports vary in detail and attribution, they align with the broader message: this is not a dormant flaw.
Recommended actions before August 7
CISA is urging federal agencies to address all three vulnerabilities by August 7. Even if you are not a federal organization, the same defensive urgency applies—especially because multiple KEVs are involved.
1) Identify affected deployments
Start by confirming whether you run:
- Langflow OSS deployments that may be exposed by default configuration. IBM indicated that default deployments are affected and that version 1.10.1 contains the fix.
- N-able N-central instances that require the corrected hotfix corresponding to CVE-2026-18577, not only the initial remediation for CVE-2026-18556.
- Apache Tomcat clusters configured with EncryptInterceptor, where CVE-2026-34486 and its underlying behavior changes may apply.
2) Patch using the vendor-provided guidance
For each product, follow the vendor’s release notes and upgrade paths. In particular, N-able’s note about an incomplete initial fix means you should validate that the system is truly patched to the bypass-resistant state.
3) Monitor for exploit attempts
Because proof-of-concept code and active exploitation have both been discussed in relation to these CVEs, monitoring matters. Look for suspicious API calls, authentication anomalies, and signs consistent with remote code execution attempts.
4) Review network exposure
At least one issue in the Langflow chain involves an unauthenticated endpoint, meaning exposure can turn a server into an immediate target. Reducing public exposure and enforcing strict access controls can lower risk while patches are rolled out.
Bottom line
CISA’s warning ties together three exploited vulnerabilities across Langflow N-central Tomcat. The Langflow issue centers on unauthenticated API chaining leading to remote code execution. The N-central weakness is an authentication bypass that attackers used for administrative access. The Tomcat flaw involves an EncryptInterceptor bypass that can enable unauthenticated remote code execution under certain cluster conditions.
With CISA urging remediation by August 7 and all three CVEs now appearing in the KEV context, the safest approach is simple: inventory affected systems, patch promptly, and validate that the security fixes fully mitigate the reported bypasses.
Source: https://www.securityweek.com/cisa-warns-of-exploited-langflow-n-central-and-tomcat-vulnerabilities/
