CVE-2026-58182 Overview
CVE-2026-58182 affects the ts_lua plugin in Apache Traffic Server (ATS), a widely deployed reverse and forward HTTP proxy. The plugin mishandles initialization, transform context, and per-instance state, which allows remote attackers to trigger uncontrolled resource consumption over the network without authentication. The flaw is tracked as [CWE-400] and impacts availability of the proxy service. Affected releases span three major branches: 8.0.0 through 8.1.9, 9.0.0 through 9.2.14, and 10.0.0 through 10.1.3. The Apache Software Foundation has published fixes in versions 9.2.15 and 10.1.4.
Critical Impact
Unauthenticated remote attackers can exhaust proxy resources through crafted requests, degrading or disrupting HTTP traffic delivery for all downstream clients.
Affected Products
- Apache Traffic Server 8.0.0 through 8.1.9
- Apache Traffic Server 9.0.0 through 9.2.14
- Apache Traffic Server 10.0.0 through 10.1.3
Discovery Timeline
- 2026-07-29 - CVE-2026-58182 published to NVD
- 2026-07-30 - Last updated in NVD database
Technical Details for CVE-2026-58182
Vulnerability Analysis
The ts_lua plugin embeds a Lua runtime inside Apache Traffic Server, enabling operators to script request and response handling. The vulnerability originates in how the plugin manages three distinct lifecycle boundaries: plugin initialization, transform context creation for streaming body modification, and per-instance state maintained across requests. Improper handling in these boundaries permits state and resources to leak or accumulate as attacker-controlled traffic passes through the proxy.
Because the flaw sits in the request-processing path of an internet-facing proxy, exploitation requires only network reachability. No credentials or user interaction are needed. The Apache advisory classifies the issue under uncontrolled resource consumption, indicating that repeated requests progressively degrade proxy capacity rather than achieving code execution or data disclosure.
Root Cause
The defect stems from lifecycle mismanagement inside ts_lua. Transform contexts and per-instance Lua state are not correctly bound to the request scope, and initialization paths do not consistently release or reuse resources. Under repeated invocation, the plugin retains memory, coroutines, or handler state that should have been reclaimed, producing an unbounded growth pattern in the ATS worker process.
Attack Vector
An attacker sends crafted HTTP requests to any Traffic Server instance that loads the ts_lua plugin. Repeated requests that exercise the affected initialization or transform paths cause the proxy to consume progressively more memory or scheduling resources. When capacity is exhausted, the server slows or stops serving legitimate traffic. Because reverse proxies typically front many origin services, a single vulnerable ATS node can affect numerous downstream applications.
No verified public exploit code exists for CVE-2026-58182 at the time of publication. Technical details are available in the Apache Security Mailing List Thread.
Detection Methods for CVE-2026-58182
Indicators of Compromise
- Sustained growth of resident memory (RSS) in traffic_server worker processes without corresponding traffic increase.
- Rising latency, connection queuing, or 5xx responses on proxy endpoints that route through ts_lua handlers.
- Repeated inbound requests to URIs or hosts mapped to ts_lua scripts from a narrow set of source addresses.
Detection Strategies
- Inventory ATS deployments and confirm plugin loading of ts_lua in plugin.config or per-remap @plugin=tslua.so entries.
- Compare running binary versions against fixed releases 9.2.15 and 10.1.4 using traffic_server -V output collected by configuration management.
- Correlate proxy access logs with process memory metrics to identify request patterns that precede resource growth.
Monitoring Recommendations
- Alert on traffic_server memory or file-descriptor thresholds and on abrupt drops in successful transaction rate.
- Enable ATS metrics export (traffic_ctl metric) and forward proxy health counters to a centralized analytics platform for baselining.
- Track request rates per remap rule that invokes ts_lua to detect abnormal concentrations of traffic against scripted endpoints.
How to Mitigate CVE-2026-58182
Immediate Actions Required
- Upgrade Apache Traffic Server to version 9.2.15 or 10.1.4, which contain the vendor fix.
- Identify any custom or third-party ts_lua scripts and review them for hot-path resource allocation before redeployment.
- Place rate limits or WAF policies in front of ATS endpoints backed by ts_lua handlers until patching completes.
Patch Information
The Apache Software Foundation released 9.2.15 for the 9.x branch and 10.1.4 for the 10.x branch to remediate CVE-2026-58182. The 8.x branch is no longer maintained and did not receive a fix; operators still running 8.0.0 through 8.1.9 must migrate to a supported branch. Patch details and source packages are referenced in the Apache Security Mailing List Thread.
Workarounds
- Temporarily unload the ts_lua plugin by commenting the corresponding entries in plugin.config and per-remap @plugin=tslua.so directives, then reload with traffic_ctl config reload.
- Restrict inbound access to remap rules that depend on ts_lua using upstream ACLs or ip_allow.yaml until the upgrade is deployed.
- Schedule periodic restart of traffic_server workers as a stopgap to bound cumulative resource growth on unpatched hosts.
# Verify running version and confirm ts_lua plugin usage before upgrading
traffic_server -V
grep -R "tslua.so" /etc/trafficserver/
# After installing the fixed package, reload configuration
traffic_ctl config reload
traffic_ctl metric get proxy.process.http.current_client_connections
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
