---
id: "CVE-2026-111817"
kind: "vulnerability"
aliases: ["CVE-2026-111817"]
title: "Apache Traffic Server: dropped chunked trailers can stall proxied transfers until timeout"
severity: "medium"
cvss: 6.9
epss: 0.00262
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["apache-traffic-server", "reverse-proxy", "runtime", "self-hosted"]
not_affected_if: ["default-config", "not-proxying-chunked-traffic"]
published_at: "2026-10-21T20:17:23+00:00"
first_seen_at: "2026-10-23T21:57:29+00:00"
updated_at: "2026-10-25T03:38:58+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111817", "first_seen_at": "2026-10-23T21:57:29+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-111817", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# Apache Traffic Server: dropped chunked trailers can stall proxied transfers until timeout

Apache Traffic Server waits for trailer bytes it has already removed from a chunked transfer, so the response stalls until the connection times out. An attacker who can send such traffic can tie up connections and degrade availability; the sources do not describe code execution or data exposure.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Traffic Server version with `traffic_server -V` or the installed package version.
- Check whether `proxy.config.http.drop_chunked_trailers` is enabled in `records.yaml` or `records.config`; on 10.x it is on by default.

## Fix

- Upgrade Apache Traffic Server 10.x installs to `10.1.5` or `10.2.1`.
- Upgrade 9.2.x installs in the affected range (`9.2.5` through `9.2.15`) to a fixed release; the sources do not name the fixed 9.2 version.
- On 8.1.11 or 9.2.x, disable `proxy.config.http.drop_chunked_trailers` if upgrading is not possible.

## Timeline

- 2026-10-23T21:57:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111817
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-111817

## From the sources

Apache Traffic Server can stall a chunked transfer that it passes through with its trailers removed (proxy.config.http.drop_chunked_trailers) until the connection times out, because it waits for the trailer bytes it has already dropped. Trailer dropping is on by default in 10.x. In 8.1.11 and 9.2.x it is off by default, and those versions are affected only if it is enabled.



This issue affects Apache Traffic Server: 8.1.11, from 9.2.5 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.



Users are recommended to upgrade to version 10.1.5 or 10.2.1, which fix the issue.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_