CVE-2026-58181 Overview
CVE-2026-58181 is a stack-based vulnerability in the Apache Traffic Server uri_signing and url_sig plugins. Attacker-controlled input can exhaust the stack or crash the process, resulting in denial of service. The flaw is classified as a stack-based buffer overflow ([CWE-121]) and is exploitable remotely without authentication or user interaction. Affected releases include Apache Traffic Server 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 released fixes in versions 9.2.15 and 10.1.4.
Critical Impact
Remote attackers can crash Apache Traffic Server instances that load the uri_signing or url_sig plugins, causing service outages for downstream applications and CDN edge traffic.
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-2026-58181 published to NVD
- 2026-07-30 - Last updated in NVD database
Technical Details for CVE-2026-58181
Vulnerability Analysis
Apache Traffic Server ships two optional plugins, uri_signing and url_sig, that validate signed URLs for content authorization. Both plugins parse untrusted request data during signature verification. The parsers do not adequately bound recursion or stack allocations when processing malformed input. An attacker can send a specifically crafted HTTP request that drives the parser into unbounded stack growth or an out-of-bounds stack write. The result is process termination or an availability failure of the proxy.
Because Apache Traffic Server is commonly deployed as a caching reverse proxy or CDN edge node, a crash affects all clients routed through the instance. Repeated exploitation sustains a denial-of-service condition against downstream origins.
Root Cause
The root cause is a stack-based buffer overflow ([CWE-121]) inside the signature validation logic of the uri_signing and url_sig plugins. Input parsing does not enforce depth or length limits before allocating stack space or invoking recursive routines. Attacker input therefore controls the volume of stack consumed during request handling.
Attack Vector
Exploitation requires network access to a Traffic Server instance with either plugin enabled. No credentials or user interaction are required. The attacker sends a crafted HTTP request whose URI or signature payload triggers excessive stack usage in the plugin's parser. Refer to the Apache Mailing List Thread for the vendor's technical description.
No verified proof-of-concept code has been published. The vulnerability mechanism is described in prose here rather than reproduced from unverified sources.
Detection Methods for CVE-2026-58181
Indicators of Compromise
- Unexpected traffic_server process crashes or restarts logged in diags.log or systemd journal.
- HTTP 5xx spikes correlated with requests carrying oversized or malformed signature parameters against endpoints protected by uri_signing or url_sig.
- Core dumps referencing plugin symbols such as url_sig.so or uri_signing.so in stack traces.
Detection Strategies
- Inventory Apache Traffic Server nodes and identify which instances load the uri_signing or url_sig plugin in plugin.config or remap.config.
- Alert on abnormal restart counts or crash signals for the traffic_server binary across the fleet.
- Inspect access logs for anomalous URI lengths, unusual query parameters, or repeated malformed signature tokens from a single source.
Monitoring Recommendations
- Forward Traffic Server diagnostic logs and process supervision events to a central SIEM for correlation.
- Track request-rate anomalies to signed URL endpoints and alert on sudden spikes from single IP addresses or ASNs.
- Monitor upstream health checks and origin error rates for cascading failures caused by proxy crashes.
How to Mitigate CVE-2026-58181
Immediate Actions Required
- Upgrade Apache Traffic Server to version 9.2.15 or 10.1.4 on all affected nodes.
- For 8.x deployments, plan migration to a supported fixed release since 8.x is within the vulnerable range and no fix version is listed.
- Restrict network exposure of Traffic Server management and plugin-protected endpoints to trusted networks pending patching.
Patch Information
The Apache Software Foundation fixed CVE-2026-58181 in Apache Traffic Server 9.2.15 and 10.1.4. Users of any 8.x, 9.x prior to 9.2.15, or 10.x prior to 10.1.4 release must upgrade. See the Apache Mailing List Thread for the official advisory.
Workarounds
- If patching cannot be completed immediately, disable the uri_signing and url_sig plugins in plugin.config and remap.config until upgrades are applied.
- Place a Web Application Firewall in front of Traffic Server to filter oversized or malformed signed URL parameters.
- Rate-limit requests to signed URL endpoints to reduce the impact of repeated crash attempts.
# Verify installed Apache Traffic Server version
traffic_server -V
# Check whether vulnerable plugins are loaded
grep -E 'uri_signing|url_sig' /etc/trafficserver/plugin.config /etc/trafficserver/remap.config
# Temporary mitigation: comment out plugin lines, then reload
sudo traffic_ctl config reload
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
