CVE-2026-16127: zevorn rt-claw SSRF Vulnerability

CVE-2026-16127 Overview

CVE-2026-16127 is a server-side request forgery (SSRF) vulnerability in the zevorn rt-claw project through version 0.2.0. The flaw resides in the claw_net_get and claw_net_post functions within claw/tools/tool_net.c, part of the http_request component. Attackers can manipulate the url argument to coerce the application into issuing arbitrary HTTP requests on their behalf. The vulnerability is remotely exploitable without authentication or user interaction, and a public exploit is available. The maintainer was notified through an issue report but has not responded at the time of disclosure.

Critical Impact
Remote unauthenticated attackers can abuse the vulnerable HTTP request functions to reach internal services, exfiltrate metadata, or pivot into otherwise unreachable network segments.

Affected Products

zevorn rt-claw versions up to and including 0.2.0
Component: http_request (claw/tools/tool_net.c)
Affected functions: claw_net_get and claw_net_post

Discovery Timeline

2026-07-18 - CVE-2026-16127 published to the National Vulnerability Database (NVD)
2026-07-20 - Last updated in NVD database

Technical Details for CVE-2026-16127

Vulnerability Analysis

The vulnerability is classified under CWE-918: Server-Side Request Forgery. The claw_net_get and claw_net_post functions in claw/tools/tool_net.c accept an attacker-controllable url argument and forward it to the underlying HTTP client without adequate validation. An attacker supplying a crafted URL forces the application to issue outbound HTTP requests to targets of the attacker's choosing.

The attack requires no authentication or user interaction and can be executed over the network. Because the request originates from the server hosting rt-claw, attackers can target loopback interfaces, private RFC1918 subnets, cloud metadata endpoints, and other services that trust internal traffic. Public exploit details are indexed on VulDB and the affected code is available in the rt-claw GitHub repository.

Root Cause

The root cause is missing allow-list validation of the url parameter passed to claw_net_get and claw_net_post. The functions trust caller-supplied URLs and do not restrict schemes, hostnames, or IP ranges before dispatching the request.

Attack Vector

An attacker submits a crafted URL to any interface that feeds the url argument into the vulnerable request functions. The server then issues the outbound request, returning content or side effects that the attacker can observe. Refer to the public issue tracker for reproduction context.

No verified proof-of-concept code is published in the enriched data. See the VulDB vulnerability details for further technical context.

Detection Methods for CVE-2026-16127

Indicators of Compromise

Outbound HTTP requests from the rt-claw host to internal IP ranges such as 127.0.0.0/8, 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16
Requests originating from rt-claw to cloud metadata endpoints such as 169.254.169.254
Unusual URL schemes (for example file://, gopher://, dict://) appearing in application logs referencing claw_net_get or claw_net_post

Detection Strategies

Instrument the http_request component to log the full url argument passed to claw_net_get and claw_net_post for later review.
Deploy egress firewall rules that alert when the rt-claw process contacts non-approved destinations.
Correlate web-facing request logs with outbound network telemetry to identify attacker-controlled URLs reflected into internal traffic.

Monitoring Recommendations

Forward network flow data and process-level connection events to a central data lake for retrospective SSRF hunting.
Alert on any access attempts to cloud instance metadata services from application workloads that do not require them.
Monitor for repeated failed outbound connections that suggest SSRF-based internal port scanning.

How to Mitigate CVE-2026-16127

Immediate Actions Required

Restrict network egress from hosts running rt-claw to an explicit allow-list of required destinations.
Block the rt-claw process from reaching cloud metadata endpoints and internal management interfaces.
Remove or disable any exposed interface that forwards untrusted input into claw_net_get or claw_net_post until a patched release is available.

Patch Information

No vendor patch is available at the time of publication. The maintainer has been notified via GitHub issue #139 but has not responded. Track the rt-claw repository for future releases addressing the SSRF condition.

Workarounds

Validate the url argument against a strict allow-list of schemes (http, https) and approved hostnames before invoking the vulnerable functions.
Resolve target hostnames and reject responses that map to loopback, link-local, or private address ranges prior to issuing the request.
Run rt-claw inside a network namespace or container with egress restricted to required external services only.

bash

# Example iptables egress restriction for the rt-claw host
iptables -A OUTPUT -d 127.0.0.0/8 -j REJECT
iptables -A OUTPUT -d 10.0.0.0/8 -j REJECT
iptables -A OUTPUT -d 172.16.0.0/12 -j REJECT
iptables -A OUTPUT -d 192.168.0.0/16 -j REJECT
iptables -A OUTPUT -d 169.254.169.254/32 -j REJECT