CVE-2026-52863
Memory corruption could lead to crash and denial of service
Description
In NLnet Labs Unbound 1.25.0 up to and including 1.25.1, a fix that makes the 'respip' and 'dns64' modules work together, creates a shallow copy of the view name in effect that could lead to memory corruption if the owner of the original view name is jostled out when Unbound is under pressure. Unbound needs to be configured with one of 'respip'/'rpz' modules, together with a module that can attach subqueries (respip CNAME redirection, dns64, subnetcache) and a configured 'access-control-view' while Unbound is under pressure so that joslte logic kicks in and starts dropping slow queries. The subquery is getting a shallow copy of the view name and if the super query which owns the view name is jostled out, memory corruption can occur. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. Debug memory builds (e.g., ASAN) that catch the free terminate the server.
INFO
Published Date :
July 22, 2026, 2:17 p.m.
Last Modified :
July 22, 2026, 2:17 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 206fc3a0-e175-490b-9eaa-a5738056c9f6 | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Unbound to the latest available version.
- Apply configuration changes as recommended by the vendor.
- Test the application thoroughly after updating.
- Monitor system stability.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-52863.
| URL | Resource |
|---|---|
| https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-52863.txt |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-52863 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-52863
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-52863 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-52863 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jul. 22, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'NLnet Labs', 'product': 'Unbound', 'versions': [{'status': 'affected', 'version': '1.25.0', 'lessThan': '1.25.2', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added Description In NLnet Labs Unbound 1.25.0 up to and including 1.25.1, a fix that makes the 'respip' and 'dns64' modules work together, creates a shallow copy of the view name in effect that could lead to memory corruption if the owner of the original view name is jostled out when Unbound is under pressure. Unbound needs to be configured with one of 'respip'/'rpz' modules, together with a module that can attach subqueries (respip CNAME redirection, dns64, subnetcache) and a configured 'access-control-view' while Unbound is under pressure so that joslte logic kicks in and starts dropping slow queries. The subquery is getting a shallow copy of the view name and if the super query which owns the view name is jostled out, memory corruption can occur. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. Debug memory builds (e.g., ASAN) that catch the free terminate the server. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-416 Added Reference https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-52863.txt