How severe is CVE-2026-12245?

CVE-2026-12245 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-12245 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-12245?

CVE-2026-12245 affects Nlnetlabs Nsd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-12245?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-12245 have an EU (EUVD) identifier?

Yes. CVE-2026-12245 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39183.

When was CVE-2026-12245 published?

CVE-2026-12245 was published on 2026-06-25 and last updated on 2026-06-26.

CVE-2026-12245

CVE-2026-12245 is a high-severity vulnerability in Nlnetlabs Nsd with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-39183
Weakness: CWE-416
Affected product: Nlnetlabs Nsd
Published: 2026-06-25
Last modified: 2026-06-26

Description

NSD from version 4.13.0 has a heap use-after-free bug in logging errors on TLS connections, causing a crash of the server process, which can be triggered trivially by sending a DNS query over a DoT connection, and closing the connection without reading the response.

Frequently asked questions

What is CVE-2026-12245?: NSD from version 4.13.0 has a heap use-after-free bug in logging errors on TLS connections, causing a crash of the server process, which can be triggered trivially by sending a DNS query over a DoT connection, and closing the connection without reading the response.
How severe is CVE-2026-12245?: CVE-2026-12245 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-12245 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-12245?: CVE-2026-12245 affects Nlnetlabs Nsd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-12245?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-12245 have an EU (EUVD) identifier?: Yes. CVE-2026-12245 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39183.
When was CVE-2026-12245 published?: CVE-2026-12245 was published on 2026-06-25 and last updated on 2026-06-26.

References

https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-12245.txt

Affected products (1)

cpe:2.3:a:nlnetlabs:nsd:*:*:*:*:*:*:*:*

More vulnerabilities in Nlnetlabs Nsd

CVE-2026-12244 — High (CVSS 8.8): If NSD is configured as secondary for a zone, the primary of that zone can crash NSD with an AXFR containing a DNS…
CVE-2026-12246 — High (CVSS 8.1): NSD version 4.14.0 introduced a bug where a specially crafted APL RR, with an adflength larger than permitted for the…
CVE-2026-12490 — High (CVSS 7.5): When a provide-xfr is given with a tls-auth-name, a secondary requesting a transfer should provide a client certificate…
CVE-2016-6173 — High (CVSS 7.5): NSD before 4.1.11 allows remote DNS master servers to cause a denial of service (/tmp disk consumption and slave server…
CVE-2013-5661 — Medium (CVSS 5.9): Cache Poisoning issue exists in DNS Response Rate Limiting.
CVE-2012-2978 — Medium (CVSS 5.0): query.c in NSD 3.0.x through 3.0.8, 3.1.x through 3.1.1, and 3.2.x before 3.2.12 allows remote attackers to cause a…

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Other CWE-416 (Use After Free) vulnerabilities

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CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…

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