CVE-2020-25686A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the…
- 3.7LowCVSS base score
- 5.5%Exploitation in 30 daysEPSS · top 7.1% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By redhat
- 4 months later
· 4 months later
Published
- 5 years later
· 5 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Low3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |
- EPSS (exploitation in 30 days)
- 5.5% · top 7.1% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 3.7.
Affected products
dnsmasq
- affected dnsmasq 2.83
References
References8
- https://www.jsof-tech.com/disclosures/dnspooq/ (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.redhat.com/show_bug.cgi?id=1890125 (opens in a new tab)x_refsource_MISCx_transferred
- FEDORA-2021-84440e87ba (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- GLSA-202101-17 (opens in a new tab)vendor-advisoryx_refsource_GENTOOx_transferred
- DSA-4844 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
- FEDORA-2021-2e4c3d5a9d (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61 (opens in a new tab)x_refsource_MISCx_transferred
- https://www.kb.cert.org/vuls/id/434904 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2020-18348 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2020-25686)Record last updated .