CVE-2026-3104
Analyzed Analyzed - Analysis Complete
Memory Leak in BIND 9 Resolver via Crafted Domain Query

Publication date: 2026-03-25

Last updated on: 2026-05-21

Assigner: Internet Systems Consortium (ISC)

Description
A specially crafted domain can be used to cause a memory leak in a BIND resolver simply by querying this domain. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.
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Meta Information
Published
2026-03-25
Last Modified
2026-05-21
Generated
2026-06-16
AI Q&A
2026-03-25
EPSS Evaluated
2026-06-15
NVD
CVE-2026-3104
EUVD
EUVD-2026-15410
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
isc bind From 9.20.0 (inc) to 9.20.21 (exc)
isc bind From 9.21.0 (inc) to 9.21.20 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-401 The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
CWE-772 The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
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Executive Summary

This vulnerability involves a specially crafted domain name that can cause a memory leak in the BIND DNS resolver when queried.

It affects specific versions of BIND 9, namely versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1.

Other versions such as 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are not affected.

Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

Detection Guidance

This vulnerability causes a memory leak in the BIND resolver process named, leading to unbounded growth in Resident Set Size (RSS) memory usage.

To detect this vulnerability on your system, monitor the memory usage of the named process for unusual or continuous growth, which may indicate the memory leak is active.

You can use commands such as:

  • Linux: `ps aux | grep named` to check memory usage of the named process.
  • Linux: `top` or `htop` to observe real-time memory consumption of named.
  • Linux: `pmap <pid_of_named>` to get detailed memory map of the named process.
  • Linux: `cat /proc/<pid_of_named>/status | grep VmRSS` to check Resident Set Size memory.

Additionally, if the named process crashes with an assertion failure during shutdown or reload, this may also indicate the presence of the vulnerability.

Mitigation Strategies

The recommended immediate mitigation step is to upgrade your BIND resolver software to a patched version.

  • Upgrade to BIND versions 9.20.21, 9.21.20, or 9.20.21-S1 (Supported Preview Edition) as these versions contain the fix for the memory leak.

No workarounds are known for this vulnerability, so upgrading is the only effective mitigation.

Monitor the named process for abnormal memory usage and avoid restarting or reloading the service while the leak is active to prevent assertion failures.

Impact Analysis

The vulnerability can lead to a memory leak in the BIND resolver, which may cause the affected system to consume increasing amounts of memory over time.

This can degrade system performance or potentially cause a denial of service if the memory exhaustion becomes severe.

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