How severe is CVE-2020-25686?

CVE-2020-25686 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2020-25686 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-2020-25686?

CVE-2020-25686 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-2020-25686?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-25686 published?

CVE-2020-25686 was published on 2021-01-20 and last updated on 2026-06-17.

CVE-2020-25686

CVE-2020-25686 is a low-severity vulnerability in Thekelleys Dnsmasq with a CVSS 3.x base score of 3.7. 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-358.

Key facts

Severity: Low (CVSS 3.x base score 3.7)
CVSS v2: 4.3
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-358
Affected product: Thekelleys Dnsmasq
Published: 2021-01-20
Last modified: 2026-06-17

Description

A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. If chained with CVE-2020-25684, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

Frequently asked questions

What is CVE-2020-25686?: A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. If chained with CVE-2020-25684, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
How severe is CVE-2020-25686?: CVE-2020-25686 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2020-25686 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-2020-25686?: CVE-2020-25686 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-2020-25686?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-25686 published?: CVE-2020-25686 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:10.0:*:*:*:*:*:*:*
cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*

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 →

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