How severe is CVE-2011-0520?

CVE-2011-0520 has a CVSS 2.0 base score of 7.5, rated high severity.

Is CVE-2011-0520 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-0520?

CVE-2011-0520 primarily affects Maradns. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-0520?

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.

When was CVE-2011-0520 published?

CVE-2011-0520 was published on 2011-01-28 and last updated on 2026-06-16.

CVE-2011-0520

CVE-2011-0520 is a high-severity vulnerability in Maradns with a CVSS 2.0 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-119.

Key facts

Severity: High (CVSS 2.0 base score 7.5)
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-119
Affected product: Maradns
Published: 2011-01-28
Last modified: 2026-06-16

Description

The compress_add_dlabel_points function in dns/Compress.c in MaraDNS 1.4.03, 1.4.05, and probably other versions allows remote attackers to cause a denial of service (segmentation fault) and possibly execute arbitrary code via a long DNS hostname with a large number of labels, which triggers a heap-based buffer overflow.

Frequently asked questions

What is CVE-2011-0520?: The compress_add_dlabel_points function in dns/Compress.c in MaraDNS 1.4.03, 1.4.05, and probably other versions allows remote attackers to cause a denial of service (segmentation fault) and possibly execute arbitrary code via a long DNS hostname with a large number of labels, which triggers a heap-based buffer overflow.
How severe is CVE-2011-0520?: CVE-2011-0520 has a CVSS 2.0 base score of 7.5, rated high severity.
Is CVE-2011-0520 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2011-0520?: CVE-2011-0520 primarily affects Maradns. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2011-0520?: 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.
When was CVE-2011-0520 published?: CVE-2011-0520 was published on 2011-01-28 and last updated on 2026-06-16.

References

Affected products (2)

cpe:2.3:a:maradns:maradns:1.4.03:*:*:*:*:*:*:*
cpe:2.3:a:maradns:maradns:1.4.05:*:*:*:*:*:*:*

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