# CVE-2026-94300: BIND named GSS-TSIG replay heap corruption

Source: https://junglewise.ai/threats/cve-2026-94300-replaying-gss-tsig-signed-udp-messages-can-result-in-memory  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-21. Updated: 2026-10-21  
License: CC BY 4.0 with a link back

CVE-2026-94300 · Severity: high · CVSS 8.1 · Published 2026-10-21

BIND is the most widely deployed DNS server software that translates domain names into IP addresses. A flaw in BIND's handling of GSS-TSIG signed DNS messages allows an attacker who captures a signed UDP message to replay it later while the key remains valid, potentially corrupting memory and achieving remote code execution on the DNS server.

Technologies: [Isc Bind](https://junglewise.ai/threats/technologies/bind). Vendors: [Isc](https://junglewise.ai/threats/vendors/isc).

## Quick answers

**Is CVE-2026-94300 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-94300 being exploited in the wild.

**How severe is CVE-2026-94300?** High severity, with a CVSS score of 8.1, published 21 October 2026.

**Which products and versions are affected?** Isc Bind 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, 9.20.9-S1 through 9.20.29-S1.

**Is there a fix for CVE-2026-94300?** Yes: fixed in BIND 9.18.51, 9.20.30, 9.21.27, 9.18.51-S1, 9.20.30-S1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-94300 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-94300?** Check whether you run Isc Bind at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in BIND 9.18.51, 9.20.30, 9.21.27, 9.18.51-S1, 9.20.30-S1

## Technical details

GSS-TSIG replay vulnerability in BIND's named daemon: an attacker can capture and replay previously signed UDP TSIG messages before the negotiated key expires. By combining replay with crafted queries to a zone under attacker control, remote code execution may be achieved through heap corruption. This affects BIND 9.11.0–9.21.26 and several supported security release branches.

## Affected products

- ISC BIND 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, 9.20.9-S1 through 9.20.29-S1

## Timeline

- 2026-10-21: disclosed

## References

- [https://downloads.isc.org/isc/bind9/9.20.30](https://downloads.isc.org/isc/bind9/9.20.30)
- [https://downloads.isc.org/isc/bind9/9.21.27](https://downloads.isc.org/isc/bind9/9.21.27)

## Related threats

- [BIND assertion failure with redirect zone and qname-minimization](https://junglewise.ai/threats/cve-2026-96888-a-bind-resolver-that-is-configured-with-both-a-redirect-zone-and)
- [ISC BIND resolver DNS message processing denial of service](https://junglewise.ai/threats/cve-2026-19630-in-a-bind-resolver-inbound-dns-protocol-messages-with-a)
- [ISC BIND denial of service via TKEY queries](https://junglewise.ai/threats/cve-2015-5477-isc-bind-data-processing-errors-vulnerability)
- [BIND resolver crash on DNSSEC-signed wildcard with NSEC mismatch](https://junglewise.ai/threats/cve-2026-80274-bind-resolver-crash-on-dnssec-signed-wildcard-with-nsec-mismatch)
- [ISC BIND DNSSEC validation bypass with NSEC3 forgery](https://junglewise.ai/threats/cve-2026-77119-isc-bind-dnssec-validation-bypass-with-nsec3-forgery)