CVE-2026-12246Network attack vector

Stack overwrite via oversized APL address length

Published Jun 25, 2026 · Updated Jun 25, 2026

Stack overflow in NLnet Labs NSD 4.14.0 through 4.14.2 allows remote authenticated users to overwrite stack memory via a crafted APL RR. When writing a zone file, the APL rdata path fails to reject an adflength above the address-family limit and writes up to 111 attacker-controlled bytes to the stack. Reachability requires a configured primary inside NSD's trust boundary to supply the rogue record to a secondary, particularly in multi-tenant DNS deployments.

CVSS severity7.2
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack overflow in NLnet Labs NSD 4.14.0 through 4.14.2 allows remote authenticated users to overwrite stack memory via a crafted APL RR. When writing a zone file, the APL rdata path fails to reject an adflength above the address-family limit and writes up to 111 attacker-controlled bytes to the stack. Reachability requires a configured primary inside NSD's trust boundary to supply the rogue record to a secondary, particularly in multi-tenant DNS deployments.

The record

CVE
CVE-2026-12246
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
NLnet Labs
Product
NSD
Classifications
CWE-20, CWE-120
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.14.0 <4.14.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

NLnet Labs · NSDversion=4.14.0 <4.14.3

Published CVSS scores

7.2NLnet LabsCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
8.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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