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Vulnerability record · CVE-2021-45951 · published 1 January 2022

CVE-2021-45951: Thekelleys dnsmasq out-of-bounds write vulnerability

Thekelleys · Dnsmasq

Dnsmasq 2.86 has a heap-based buffer overflow in check_bad_address (called from check_for_bogus_wildcard and FuzzCheckForBogusWildcard). NOTE: the vendor's position is that CVE-2021-45951 through CVE-2021-45957 "do not represent real vulnerabilities, to the best of our knowledge.

9.8 CVSS 3.1 Critical EPSS 2.6% · top 15.3% CWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score, v2 7.5
2.6%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

Dnsmasq 2.86 has a heap-based buffer overflow in check_bad_address (called from check_for_bogus_wildcard and FuzzCheckForBogusWildcard). NOTE: the vendor's position is that CVE-2021-45951 through CVE-2021-45957 "do not represent real vulnerabilities, to the best of our knowledge.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35868 ExploitIssue TrackingThird Party Advisory
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/dnsmasq/OSV-2021-924.yaml Third Party Advisory
https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2022q1/016162.html Mailing ListThird Party Advisory
https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2022q1/016164.html Mailing ListThird Party Advisory
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35868 ExploitIssue TrackingThird Party Advisory
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/dnsmasq/OSV-2021-924.yaml Third Party Advisory
https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2022q1/016162.html Mailing ListThird Party Advisory
https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2022q1/016164.html Mailing ListThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-45952Thekelleys dnsmasq out-of-bounds write vulnerabilityDnsmasq 2.86 has a heap-based buffer overflow in dhcp_reply (called from dhcp_packet and FuzzDhcp). NOTE: the vendor's position is that CVE-2021-4595…EPSS 2.6%9.8CVE-2021-45953Thekelleys dnsmasq out-of-bounds write vulnerabilityDnsmasq 2.86 has a heap-based buffer overflow in extract_name (called from hash_questions and fuzz_util.c). NOTE: the vendor's position is that CVE-2…EPSS 2.6%9.8CVE-2021-45954Thekelleys dnsmasq out-of-bounds write vulnerabilityDnsmasq 2.86 has a heap-based buffer overflow in extract_name (called from answer_auth and FuzzAuth). NOTE: the vendor's position is that CVE-2021-45…EPSS 2.6%9.8CVE-2021-45955Thekelleys dnsmasq out-of-bounds write vulnerabilityDnsmasq 2.86 has a heap-based buffer overflow in resize_packet (called from FuzzResizePacket and fuzz_rfc1035.c) because of the lack of a proper boun…EPSS 2.5%9.8CVE-2021-45956Thekelleys dnsmasq out-of-bounds write vulnerabilityDnsmasq 2.86 has a heap-based buffer overflow in print_mac (called from log_packet and dhcp_reply). NOTE: the vendor's position is that CVE-2021-4595…EPSS 2.6%9.8CVE-2021-45957Thekelleys dnsmasq out-of-bounds write vulnerabilityDnsmasq 2.86 has a heap-based buffer overflow in answer_request (called from FuzzAnswerTheRequest and fuzz_rfc1035.c). NOTE: the vendor's position is…EPSS 2.4%9.8CVE-2017-14491dnsmasq heap buffer overflow via crafted DNS responsednsmasq before 2.78 contains a heap-based buffer overflow (CWE-787 out-of-bounds write) triggered by a crafted DNS response. Because dnsmasq is widel…EPSS 85%analysed9.8CVE-2017-14492dnsmasq IPv6 router advertisement heap buffer overflowdnsmasq before 2.78 contains a heap-based buffer overflow reachable through a crafted IPv6 router advertisement request. A remote, unauthenticated at…EPSS 93%analysed

Source: NIST National Vulnerability Database (record CVE-2021-45951), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.