---
id: CVE-2026-80225
title: >-
  In NLnetLabs Unbound up to and including 1.26.0, a degradation of service
  vulnerability is present in the TCP/DoT reading procedure where there is no
  limit on consecutive reads
summary: >-
  In NLnetLabs Unbound up to and including 1.26.0, a degradation of service
  vulnerability is present in the TCP/DoT reading procedure where there is no
  limit on consecutive reads. A malicious actor that can stream and sustain a
  rate of dis…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-770
  - CWE-1050
vendor: NLnet Labs
product: Unbound
affected:
  - Unbound < 1.26.1
published: '2026-09-16'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T19:41:10.423'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-80225'
references:
  - url: 'https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-80225.txt'
    label: sep@nlnetlabs.nl
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80225.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-80225'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2535055'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-80225'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-80225'
  - url: 'https://access.redhat.com/errata/RHSA-2026:68590'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-16T14:32:57.188145Z'
ingestedAt: '2026-09-16T08:52:29.598Z'
epss: 0.00312
epssPercentile: 0.24282
patched:
  - hardened_images
---

## Overview

In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the TCP/DoT reading procedure where there is no limit on consecutive reads. A malicious actor that can stream and sustain a rate of distinct uncached names over the TCP/DoT connection, monopolizes a single worker's entire event loop for as long as its writes stay ahead of the drain.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80225.json)
- **RHSA-2026:68590** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-17 · [advisory](https://access.redhat.com/errata/RHSA-2026:68590)