CVE-2026-12244Network attack vector

Server crash via truncated SVCB allocation

Published Jun 25, 2026 · Updated Jun 25, 2026

Heap overflow in NSD 4.14.0 through 4.14.2 allows remote authenticated users to crash the server via a crafted SVCB record. The SVCB RR wrapping path adds record overhead to 65,512-byte RDATA in a 16-bit length, wraps the allocation size past 65,535, and copies oversized data into the heap allocation. Reachability requires a configured primary to supply the record by AXFR to a secondary; the controlled overwrite reaches 65,509 bytes, while code execution has not been demonstrated.

CVSS severity8.7
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap overflow in NSD 4.14.0 through 4.14.2 allows remote authenticated users to crash the server via a crafted SVCB record. The SVCB RR wrapping path adds record overhead to 65,512-byte RDATA in a 16-bit length, wraps the allocation size past 65,535, and copies oversized data into the heap allocation. Reachability requires a configured primary to supply the record by AXFR to a secondary; the controlled overwrite reaches 65,509 bytes, while code execution has not been demonstrated.

The record

CVE
CVE-2026-12244
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
NLnet Labs
Product
NSD
Classifications
CWE-122, CWE-190, T1499.004
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

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.7NLnet LabsCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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-122Heap-based Buffer Overflow
CWE-190Integer Overflow or Wraparound
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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