CVE-2026-77692

Unauthenticated remote crash of named via a single DoH SIG(0) request

Public exploit available. Not confirmed exploited in the wild yet. A vendor fix is available.

CVSS 3.17.5High EPSS percentile50th0.7% chance in 30 days CISA KEVNot listedNo confirmed exploitation
Public exploit: 0 sources FixVendor fixNo build named by the sources

Published 2026-09-16Updated 2026-09-17Sources: CVE.org, NVD

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Steps

Written by AI from the record

Check whether you run bind 9 and whether its DNS-over-HTTPS endpoint is enabled and reachable from the internet.
Check the installed version with named -v or your server’s package manager.
Upgrade to 9.20.29, 9.21.26, or 9.20.29-S1, choosing the patched release for your current branch.
Restart the DNS service and confirm it is answering requests normally after the upgrade.

Vendor advisory Some work to apply

Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

An attacker can cause `named` to abort by sending a crafted DNS-over-HTTPS request with a cryptographically invalid SIG(0) record, and then closing the transport connection prematurely. This issue affects BIND 9 versions 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and 9.20.9-S1 through 9.20.27-S1.

In plain language

Written by AI from the record

bind 9 servers running versions 9.20.0-9.20.27, 9.21.0-9.21.25, or 9.20.9-S1-9.20.27-S1 can be knocked offline remotely, so affected small businesses should act now.

Unauthenticated remote denial of service in bind 9’s DNS-over-HTTPS handling: a malformed SIG(0) record followed by an abruptly closed connection triggers a null-pointer dereference and crashes named.

If you're affected

DNS service outage
Website access disruption
Email delivery disruption
Internal service interruption

What is it

This is a flaw that lets someone send one specially malformed request that makes the DNS server stop working. It is like a caller using a deliberately broken form to make a business’s switchboard shut down, preventing callers from reaching the right destination until it is restored.

Who is affected

This matters to you if you run bind 9 as a DNS server. It is only a risk when the server’s DNS-over-HTTPS endpoint is accessible to an attacker.

How urgent is it

A public exploit is available for a flaw that can remotely take the DNS service offline with a single request. There are no reported real-world attacks yet, but an affected internet-facing server should be upgraded as an urgent priority because DNS outages can immediately disrupt websites, email, and business systems.

What to do — in detail

Confirm exposure by checking the running version (named -v) and reviewing the bind 9 configuration and network controls for an enabled DNS-over-HTTPS listener reachable by untrusted networks. Affected branches are 9.20.0-9.20.27, 9.21.0-9.21.25, and 9.20.9-S1-9.20.27-S1; upgrade respectively to 9.20.29, 9.21.26, or 9.20.29-S1 using your operating system’s supported bind 9 package or ISC release process. Stay on the same release branch where possible and validate configuration syntax, service startup, and authoritative/recursive DNS responses after restarting named. No vendor workaround is known; if patching is delayed, restrict access to the DNS-over-HTTPS endpoint to trusted networks or disable that endpoint where operationally acceptable. Monitor named logs and service supervision alerts for unexpected aborts, restarts, or DNS-over-HTTPS connection failures. This CVE is not listed in CISA KEV, so no CISA due date applies.

Technical context

CVE-2026-77692 is CVSS 7.5 (High), CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. It is a CWE-476 null-pointer dereference reachable through DNS-over-HTTPS: a cryptographically invalid SIG(0) record combined with premature transport closure can abort named. No CISA KEV listing or confirmed in-the-wild exploitation is reported, although a public exploit is available. EPSS is 0.5% at the 40th percentile and flat.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS50th

Public exploit

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

0 sources with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in

EPSS

0.7% chance of exploitation activity in the next 30 days, which ranks it in the 50th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Attention now

Sustained, driven by in-the-wild reports.

Lifecycle

12 events over 1 day, from the signal feeds we watch.

2026-09-17Patch availableworkaround available, record updated
2026-09-16Patch availablepatch available, workaround available, workaround available, published, weakness classified, att&ck mapped, record updated, record updated

Affected products

ISCcommercial · USaka internet systems consortium
- BIND 9Networking Infrastructure

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Scored 7.5 by NVD.

How it is reached

Attack Vector NetworkExploitable remotely over the network without any special conditions
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required NoneNo authentication required — anyone can exploit this
User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

Confidentiality NoneNo confidentiality impact
Integrity NoneNo integrity impact
Availability HighTotal denial of service — the component is completely unavailable