CVE-2026-58183 Overview
CVE-2026-58183 is an input validation vulnerability [CWE-20] in the Apache Traffic Server (ATS) prefetch plugin. The plugin crashes when processing attacker-influenced input, resulting in a denial of service condition against the caching proxy. The flaw affects Apache Traffic Server versions 8.0.0 through 8.1.9, 9.0.0 through 9.2.14, and 10.0.0 through 10.1.3. The Apache Traffic Server project recommends upgrading to version 9.2.15 or 10.1.4, which contain the fix. The vulnerability is network-reachable, requires no privileges, and requires no user interaction.
Critical Impact
Remote attackers can crash the Apache Traffic Server prefetch plugin over the network without authentication, disrupting cached content delivery for downstream users.
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-2026-58183 published to the National Vulnerability Database
- 2026-07-30 - CVE-2026-58183 last updated in NVD
Technical Details for CVE-2026-58183
Vulnerability Analysis
Apache Traffic Server is a high-performance forward and reverse HTTP proxy. The prefetch plugin proactively fetches related content to reduce latency for subsequent client requests. The Apache Software Foundation advisory categorizes this issue as improper input validation [CWE-20] in that plugin. Malformed or attacker-shaped input reaches parsing logic that does not adequately validate its structure, causing the process handling the request to crash.
Because Apache Traffic Server sits inline for HTTP traffic in content delivery networks, edge caches, and internal proxy tiers, a crash of the prefetch code path affects availability for every client behind the affected node. Repeated exploitation produces a sustained denial of service condition.
Root Cause
The root cause is insufficient validation of input consumed by the prefetch plugin. The plugin does not sanitize or bounds-check attacker-influenced fields before acting on them, leading to an unhandled error state. Full technical specifics are available in the Apache Security Mailing List Thread.
Attack Vector
An unauthenticated remote attacker sends a crafted HTTP request that triggers the prefetch plugin's vulnerable code path. Exploitation requires the prefetch plugin to be enabled in the Apache Traffic Server configuration. No user interaction is required, and the attack traverses the network. The impact is limited to availability; the advisory does not describe confidentiality or integrity loss.
No public proof-of-concept exploit or in-the-wild exploitation has been reported for CVE-2026-58183 at the time of publication. See the Apache Security Mailing List Thread for advisory details.
Detection Methods for CVE-2026-58183
Indicators of Compromise
- Unexpected traffic_server process crashes, restarts, or core dumps on hosts running the prefetch plugin.
- Error entries in diags.log, traffic.out, or error.log referencing the prefetch plugin near request-processing failures.
- Client-visible 502 or 504 responses correlated with proxy restarts.
- Repeated requests from a single source IP immediately preceding proxy instability.
Detection Strategies
- Inventory Apache Traffic Server nodes and identify installations running versions 8.0.0–8.1.9, 9.0.0–9.2.14, or 10.0.0–10.1.3 with the prefetch plugin loaded via plugin.config or remap.config.
- Alert on anomalous restart frequency of the traffic_server service using process telemetry.
- Correlate HTTP access log spikes with proxy error logs to identify request patterns that precede crashes.
Monitoring Recommendations
- Forward Apache Traffic Server logs and process events to a centralized logging or SIEM platform for correlation.
- Track service uptime and crash counters for each proxy node as a health signal.
- Monitor upstream and downstream error rates to detect availability degradation caused by prefetch-plugin failures.
How to Mitigate CVE-2026-58183
Immediate Actions Required
- Upgrade Apache Traffic Server to version 9.2.15 or 10.1.4, which fix the issue.
- If the prefetch plugin is not required, disable it by removing its entries from plugin.config and any remap.config rules that load it, then reload the configuration.
- Restrict inbound access to Apache Traffic Server management and prefetch-related endpoints to trusted networks until patching is complete.
Patch Information
The Apache Software Foundation fixed CVE-2026-58183 in Apache Traffic Server 9.2.15 and 10.1.4. Users on the 8.x branch should migrate to a supported fixed release, since the advisory does not list a fixed 8.x version. Refer to the Apache Security Mailing List Thread for release notes and upgrade guidance.
Workarounds
- Disable the prefetch plugin in plugin.config and reload Apache Traffic Server if the feature is not in use.
- Place a validating reverse proxy or WAF in front of Apache Traffic Server to reject malformed requests targeting prefetch behavior.
- Rate-limit request sources at the network edge to reduce the impact of repeated crash attempts until the upgrade is deployed.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
