How severe is CVE-2019-25034?

CVE-2019-25034 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2019-25034 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-25034?

CVE-2019-25034 primarily affects Nlnetlabs Unbound. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-25034?

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

When was CVE-2019-25034 published?

CVE-2019-25034 was published on 2021-04-27 and last updated on 2026-06-17.

CVE-2019-25034

CVE-2019-25034 is a critical-severity vulnerability in Nlnetlabs Unbound with a CVSS 3.x base score of 9.8. 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-190.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Nlnetlabs Unbound
Published: 2021-04-27
Last modified: 2026-06-17

Description

Unbound before 1.9.5 allows an integer overflow in sldns_str2wire_dname_buf_origin, leading to an out-of-bounds write. NOTE: The vendor disputes that this is a vulnerability. Although the code may be vulnerable, a running Unbound installation cannot be remotely or locally exploited

Frequently asked questions

What is CVE-2019-25034?: Unbound before 1.9.5 allows an integer overflow in sldns_str2wire_dname_buf_origin, leading to an out-of-bounds write. NOTE: The vendor disputes that this is a vulnerability. Although the code may be vulnerable, a running Unbound installation cannot be remotely or locally exploited
How severe is CVE-2019-25034?: CVE-2019-25034 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2019-25034 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-25034?: CVE-2019-25034 primarily affects Nlnetlabs Unbound. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-25034?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2019-25034 published?: CVE-2019-25034 was published on 2021-04-27 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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Other CWE-190 (Integer Overflow or Wraparound) vulnerabilities

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