How severe is CVE-2020-25681?

CVE-2020-25681 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-25681 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 81% (100th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-25681?

CVE-2020-25681 primarily affects Thekelleys Dnsmasq. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-25681?

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-2020-25681 published?

CVE-2020-25681 was published on 2021-01-20 and last updated on 2026-06-17.

CVE-2020-25681

CVE-2020-25681 is a high-severity vulnerability in Thekelleys Dnsmasq with a CVSS 3.x base score of 8.1. Its EPSS exploit-prediction score of 81% places it in the 100th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-122.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 8.3
EPSS exploit prediction: 81% (100th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-122
Affected product: Thekelleys Dnsmasq
Published: 2021-01-20
Last modified: 2026-06-17

Description

A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in the way RRSets are sorted before validating with DNSSEC data. An attacker on the network, who can forge DNS replies such as that they are accepted as valid, could use this flaw to cause a buffer overflow with arbitrary data in a heap memory segment, possibly executing code on the machine. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Frequently asked questions

What is CVE-2020-25681?: A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in the way RRSets are sorted before validating with DNSSEC data. An attacker on the network, who can forge DNS replies such as that they are accepted as valid, could use this flaw to cause a buffer overflow with arbitrary data in a heap memory segment, possibly executing code on the machine. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
How severe is CVE-2020-25681?: CVE-2020-25681 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-25681 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 81% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-25681?: CVE-2020-25681 primarily affects Thekelleys Dnsmasq. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-25681?: 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-2020-25681 published?: CVE-2020-25681 was published on 2021-01-20 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:thekelleys:dnsmasq:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

More vulnerabilities in Thekelleys Dnsmasq

CVE-2021-45957 — Critical (CVSS 9.8): Dnsmasq 2.86 has a heap-based buffer overflow in answer_request (called from FuzzAnswerTheRequest and fuzz_rfc1035.c).…
CVE-2021-45956 — Critical (CVSS 9.8): Dnsmasq 2.86 has a heap-based buffer overflow in print_mac (called from log_packet and dhcp_reply). NOTE: the vendor's…
CVE-2021-45955 — Critical (CVSS 9.8): Dnsmasq 2.86 has a heap-based buffer overflow in resize_packet (called from FuzzResizePacket and fuzz_rfc1035.c)…
CVE-2021-45954 — Critical (CVSS 9.8): Dnsmasq 2.86 has a heap-based buffer overflow in extract_name (called from answer_auth and FuzzAuth). NOTE: the…
CVE-2021-45953 — Critical (CVSS 9.8): Dnsmasq 2.86 has a heap-based buffer overflow in extract_name (called from hash_questions and fuzz_util.c). NOTE: the…
CVE-2021-45952 — Critical (CVSS 9.8): Dnsmasq 2.86 has a heap-based buffer overflow in dhcp_reply (called from dhcp_packet and FuzzDhcp). NOTE: the vendor's…

All CVEs affecting Thekelleys Dnsmasq →

Other CWE-122 (Heap-based Buffer Overflow) vulnerabilities

CVE-2026-46752 — Critical (CVSS 10.0): Redis Lua HEAP overflow in cjson library vulnerability in Apache Kvrocks. This issue affects Apache Kvrocks: from…
CVE-2026-24822 — Critical (CVSS 10.0): Out-of-bounds Write, Heap-based Buffer Overflow vulnerability in ttttupup wxhelper (src modules). This vulnerability is…
CVE-2025-23123 — Critical (CVSS 10.0): A malicious actor with access to the management network could execute a remote code execution (RCE) by exploiting a…
CVE-2022-34819 — Critical (CVSS 10.0): A vulnerability has been identified in SIMATIC CP 1242-7 V2 (All versions < V3.3.46), SIMATIC CP 1243-1 (All versions <…
CVE-2026-44050 — Critical (CVSS 9.9): A heap-based buffer overflow in the CNID daemon comm_rcv() function in Netatalk 2.0.0 through 4.4.2 allows a remote…
CVE-2026-49841 — Critical (CVSS 9.8): FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to…

Browse all CWE-122 (Heap-based Buffer Overflow) vulnerabilities →