CISA KEV Catalog Adds N-able, Langflow, Tomcat Flaws
CISA Catalogs Actively Exploited Flaws in N-able, Langflow, Tomcat
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Executive Summary
On August 4-5, 2026, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) added three significant vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog, signaling that they are under active attack and pose a grave risk to federal networks. The vulnerabilities affect widely used enterprise products: IBM's Langflow AI platform, N-able's N-central RMM software, and Apache Tomcat. The flaws include a critical unauthenticated remote code execution (CVE-2026-9198), an authentication bypass exploited as a zero-day (CVE-2026-18556), and an encryption interceptor bypass (CVE-2026-34486). Due to confirmed in-the-wild exploitation, CISA has issued a directive requiring Federal Civilian Executive Branch (FCEB) agencies to apply patches for these vulnerabilities by August 7, 2026. Private organizations are strongly urged to prioritize remediation immediately.
Vulnerability Details
This advisory covers three distinct vulnerabilities added to the KEV catalog.
CVE-2026-9198: IBM Langflow OSS Remote Code Execution
- CVSS Score: 9.8 (Critical)
- Affected Product: IBM Langflow OSS versions 1.0.0 through 1.10.0
- Description: This is a critical unauthenticated code injection vulnerability. An attacker can chain two API endpoint flaws to achieve remote code execution (RCE) on a default Langflow deployment. The first flaw allows the attacker to generate a superuser token, which is then used with a second endpoint to execute arbitrary Python code on the server. A proof-of-concept (PoC) exploit is publicly available, significantly lowering the bar for exploitation.
CVE-2026-18556 & CVE-2026-18577: N-able N-central Authentication Bypass
- CVSS Score: 8.2 (High)
- Affected Product: N-able N-central through version 2026.1
- Description: CVE-2026-18556 is an authentication bypass that was exploited as a zero-day starting July 31, 2026. It allows an attacker to gain administrative access to the N-central Remote Monitoring and Management (RMM) platform, which is a high-value target as it provides access to the networks of many downstream customers managed by MSPs. An initial patch was found to be incomplete, leading to a bypass tracked as CVE-2026-18577, which has also been added to the KEV list. Attackers have been observed using this access to deploy remote access tools and compromise domain controllers.
CVE-2026-34486: Apache Tomcat EncryptInterceptor Bypass
- CVSS Score: 7.5 (High)
- Affected Product: Apache Tomcat versions up to 11.0.21, 10.1.54, 9.0.117
- Description: This vulnerability allows for the bypass of the
EncryptInterceptor, which can weaken data encryption and expose sensitive information. Exploitation has been attributed to a China-nexus threat actor in a widespread campaign targeting government and commercial entities in over 100 countries. The attackers used this flaw to deliver a Linux dropper and loader known as SNOWLIGHT.
Exploitation Status
All three vulnerabilities are confirmed by CISA to be actively exploited in the wild.
- CVE-2026-9198 (Langflow): Exploitation likely increased following the public release of a PoC exploit in July 2026.
- CVE-2026-18556 (N-able): Confirmed to have been exploited as a zero-day against Managed Service Providers (MSPs) before a patch was available.
- CVE-2026-34486 (Tomcat): Used by a nation-state actor between April and June 2026 as part of a large-scale espionage campaign.
Impact Assessment
The impact of these vulnerabilities is significant due to the nature of the affected products.
- Langflow: Compromise of an AI development platform could lead to theft of proprietary models, training data, and sensitive information processed by AI applications. RCE could also provide a foothold into the broader development network.
- N-able N-central: A breach of an RMM platform is a classic supply chain attack vector. Attackers can pivot from the central N-central server to compromise the networks of all connected downstream customers, leading to widespread data breaches, ransomware deployment, and espionage.
- Apache Tomcat: As a ubiquitous web server, vulnerable Tomcat instances expose organizations to web-based attacks, data interception, and server compromise. The link to a nation-state campaign indicates its utility for espionage and establishing long-term persistence in target networks.
Cyber Observables — Hunting Hints
The following patterns may help identify vulnerable or compromised systems:
- Langflow (CVE-2026-9198): Monitor web server logs for requests to Langflow API endpoints related to token generation followed by code execution endpoints. Look for suspicious Python processes spawned by the Langflow service.
- N-able (CVE-2026-18556): Audit N-central logs for unexpected administrative logins, especially from unknown IP addresses. Look for the creation of new user accounts or the deployment of scripts and remote access tools (e.g., DWAgent, AnyDesk) to managed endpoints.
- Tomcat (CVE-2026-34486): On Linux servers running Tomcat, hunt for the presence of the SNOWLIGHT dropper/loader in file systems. Monitor network traffic for anomalous connections originating from the Tomcat server process. Check for unexpected modifications to Tomcat configuration files related to interceptors.
Detection Methods
- Vulnerability Scanning: Use authenticated vulnerability scanners to identify vulnerable versions of Langflow, N-able N-central, and Apache Tomcat in your environment.
- Log Analysis: Ingest and analyze web server, application, and authentication logs from the affected products. For Langflow, search for chained API calls. For N-central, look for successful authentication events that do not correlate with known administrator activity. For Tomcat, review logs for errors or anomalies related to the
EncryptInterceptor. - Endpoint Detection and Response (EDR): Deploy EDR agents on servers hosting these applications to detect post-exploitation activity, such as suspicious process execution (
python,bash), file creation, or outbound network connections.
Remediation Steps
Immediate patching is the primary remediation for all three vulnerabilities.
- CVE-2026-9198: Upgrade IBM Langflow OSS to version 1.10.1 or later.
- CVE-2026-18556 / CVE-2026-18577: Apply the patches released by N-able for N-central. Given the history of an incomplete patch, ensure you are on the latest recommended version. After patching, review all administrative accounts for unauthorized additions.
- CVE-2026-34486: Upgrade Apache Tomcat to versions 11.0.22, 10.1.55, 9.0.118, or a later patched version.
CISA has mandated that all FCEB agencies apply these patches by August 7, 2026. All other organizations are strongly advised to follow the same timeline due to active exploitation.
Timeline of Events
Article Updates
August 6, 2026
New details on Langflow AI agent exploitation, specific Tomcat cluster impact, and clarified N-able CVE relationship.
Update Sources:
MITRE ATT&CK Mitigations
The primary mitigation is to promptly apply the security patches provided by IBM, N-able, and Apache to fix the vulnerabilities.
Mapped D3FEND Techniques:
Restrict network access to the management interfaces of N-able N-central and Langflow to only trusted IP addresses and networks. Do not expose these interfaces directly to the public internet.
Mapped D3FEND Techniques:
D3FEND Defensive Countermeasures
Given that all three vulnerabilities (CVE-2026-9198, CVE-2026-18556, CVE-2026-34486) are under active exploitation, immediate patching is the most critical action. Organizations must prioritize the deployment of security updates for IBM Langflow, N-able N-central, and Apache Tomcat. Establish an emergency patching process that can be activated when CISA adds a vulnerability to the KEV catalog. Use asset inventory and vulnerability management systems to quickly identify all affected instances within the environment. For N-able, it is especially important to verify that the latest patch addressing both CVE-2026-18556 and the bypass CVE-2026-18577 is applied. Post-patching, it is crucial to verify successful installation and hunt for signs of pre-existing compromise.
For internet-facing applications like N-able N-central and Langflow, network access controls are a vital compensating measure. Implement strict inbound traffic filtering rules on perimeter firewalls or cloud security groups. The management interfaces for these powerful platforms should never be exposed to the open internet. Access should be restricted to a small set of trusted IP addresses, such as corporate VPN endpoints or specific administrative jump hosts. This technique acts as a crucial barrier, preventing attackers from reaching the vulnerable application endpoints in the first place, thereby mitigating the risk of exploitation for both CVE-2026-9198 and CVE-2026-18556 even before a patch is applied.
To detect abuse related to the N-able authentication bypass (CVE-2026-18556), security teams should implement advanced monitoring of authentication events. Establish a baseline for normal administrative access patterns, including typical source IPs, time of day, and session duration. Configure SIEM alerts to trigger on deviations from this baseline, such as successful administrative logins from geographically impossible locations, logins outside of business hours, or an unusual spike in authentication attempts. This D3FEND technique helps identify when an attacker successfully bypasses authentication controls, enabling a faster incident response to contain the breach before the attacker can pivot to downstream customer networks.
Timeline of Events
Exploitation of N-able N-central zero-day (CVE-2026-18556) begins.
CISA adds CVE-2026-9198, CVE-2026-18556, and CVE-2026-34486 to the KEV catalog.
CISA deadline for federal agencies to apply patches for the newly added KEVs.
Sources & References(when first published)
Article Author
Jason Gomes
• Cybersecurity PractitionerCybersecurity professional with over 10 years of specialized experience in security operations, threat intelligence, incident response, and security automation. Expertise spans SOAR/XSOAR orchestration, threat intelligence platforms, SIEM/UEBA analytics, and building cyber fusion centers. Background includes technical enablement, solution architecture for enterprise and government clients, and implementing security automation workflows across IR, TIP, and SOC use cases.
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