NLnet Labs Unbound up to 1.25.0 missing special element

CVSS Meta Temp Score
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CTI Interest Score
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5.2$0-$5k0.00

Summaryinfo

A vulnerability described as problematic has been identified in NLnet Labs Unbound up to 1.25.0. This issue affects some unknown processing. Executing a manipulation can lead to improper handling of missing special element. This vulnerability is tracked as CVE-2026-32792. The attack can be launched remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in NLnet Labs Unbound up to 1.25.0. This vulnerability affects an unknown code block. The manipulation with an unknown input leads to a improper handling of missing special element vulnerability. The CWE definition for the vulnerability is CWE-166. The product receives input from an upstream component, but it does not handle or incorrectly handles when an expected special element is missing. As an impact it is known to affect availability. CVE summarizes:

NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when compiled with DNSCrypt support ('--enable-dnscrypt'). A bad DNSCrypt query could underflow Unbound's DNSCrypt packet reading procedure that may lead to heap overflow. A malicious actor can exploit the vulnerability with a single bad DNSCrypt query that its decrypted plaintext consists entirely of '0x00' bytes and does not contain the expected '0x80' marker. Unbound would then start reading more bytes than necessary until it finds a non-'0x00' byte. Based on the underlying memory allocator and the memory layout, it could lead to heap overflow while reading followed by a crash. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. If the heap overflow does not happen, Unbound's later packet checks will deny the packet. Unbound 1.25.1 contains a patch with a fix to bound reading in the given buffer space.

The weakness was disclosed by Andrew Griffiths. The advisory is shared for download at nlnetlabs.nl. This vulnerability was named CVE-2026-32792 since 05/07/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 315753 (Linux Distros Unpatched Vulnerability : CVE-2026-32792), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.25.1 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (315753) and CERT Bund (WID-SEC-2026-1599). Once again VulDB remains the best source for vulnerability data.

Affected

  • Debian Linux
  • Red Hat Enterprise Linux
  • Fedora Linux
  • Ubuntu Linux
  • Open Source Unbound
  • cPanel cPanel/WHM

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.3
NVD Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Improper handling of missing special element
CWE: CWE-166 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 315753
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-32792

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Unbound 1.25.1

Timelineinfo

05/07/2026 CVE reserved
05/20/2026 +13 days Advisory disclosed
05/20/2026 +0 days VulDB entry created
05/28/2026 +8 days VulDB entry last update

Sourcesinfo

Advisory: nlnetlabs.nl
Researcher: Andrew Griffiths
Status: Confirmed

CVE: CVE-2026-32792 (🔒)
GCVE (CVE): GCVE-0-2026-32792
GCVE (VulDB): GCVE-100-364852
CERT Bund: WID-SEC-2026-1599 - Unbound: Mehrere Schwachstellen

Entryinfo

Created: 05/20/2026 13:03
Updated: 05/28/2026 08:53
Changes: 05/20/2026 13:03 (68), 05/21/2026 20:44 (2), 05/23/2026 22:05 (11), 05/26/2026 20:34 (7), 05/28/2026 08:53 (4)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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