---
id: CVE-2026-94300
title: Concurrent GSS-TSIG messages corrupt memory
summary: >-
  Replaying GSS-TSIG signed UDP messages can result in memory corruption in
  "`named`".  An attacker who can capture a previously signed UDP message can
  replay it while the negotiated TSIG key is still valid. By also sending
  crafted queries…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-415
  - CWE-362
vendor: ISC
product: BIND 9
affected:
  - bind_9 >= 9.11.0 <= 9.18.50
  - bind_9 >= 9.20.0 <= 9.20.29
  - bind_9 >= 9.21.0 <= 9.21.26
  - bind_9 >= 9.11.3-S1 <= 9.18.50-S1
  - bind_9 >= 9.20.9-S1 <= 9.20.29-S1
published: '2026-10-21'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:45:26.540Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-94300'
references:
  - url: 'https://kb.isc.org/docs/cve-2026-94300'
    label: CVE-2026-94300
  - url: 'https://downloads.isc.org/isc/bind9/9.20.30'
  - url: 'https://downloads.isc.org/isc/bind9/9.21.27'
tags:
  - cve.org
ingestedAt: '2026-10-21T12:48:53.583Z'
---

## Overview

Replaying GSS-TSIG signed UDP messages can result in memory corruption in "`named`".  An attacker who can capture a previously signed UDP message can replay it while the negotiated TSIG key is still valid. By also sending crafted queries to a zone the attacker controls, the attacker may potentially achieve remote code execution.
This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.

## Affected

- `bind_9 >= 9.11.0 <= 9.18.50`
- `bind_9 >= 9.20.0 <= 9.20.29`
- `bind_9 >= 9.21.0 <= 9.21.26`
- `bind_9 >= 9.11.3-S1 <= 9.18.50-S1`
- `bind_9 >= 9.20.9-S1 <= 9.20.29-S1`

## Remediation

Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.30, 9.21.27, or 9.20.30-S1.

### Workarounds

No workarounds known.