---
id: CVE-2026-111808
title: >-
  Apache Traffic Server: HTTP/2 DATA frame padding underflow lets a client
  trigger backend worker-pool exhaustion
summary: >-
  Apache Traffic Server can be used to exhaust an HTTP/1.1 origin's worker pool
  via a malformed padded HTTP/2 DATA frame.




  This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from
  9.0.0 through 9.2.15, from 10.0.0 throug…
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-191
vendor: Apache Software Foundation
product: Apache Traffic Server
affected:
  - apache_traffic_server >= 8.0.0 <= 8.1.11
  - apache_traffic_server >= 9.0.0 <= 9.2.15
  - apache_traffic_server >= 10.0.0 <= 10.1.4
  - apache_traffic_server 10.2.0
published: '2026-10-21'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T19:11:59.516Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-111808'
references:
  - url: 'https://lists.apache.org/thread/r95dq29ywcd1f4x30snxlqmb12z4s4kc'
tags:
  - cve.org
ingestedAt: '2026-10-21T20:11:44.911Z'
---

## Overview

Apache Traffic Server can be used to exhaust an HTTP/1.1 origin's worker pool via a malformed padded HTTP/2 DATA frame.



This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.



Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

## Affected

- `apache_traffic_server >= 8.0.0 <= 8.1.11`
- `apache_traffic_server >= 9.0.0 <= 9.2.15`
- `apache_traffic_server >= 10.0.0 <= 10.1.4`
- `apache_traffic_server 10.2.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.