CVE-2020-25687

MEDIUMNVD 5.99.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 87% probability of exploitation within the next 30 days (top 0.3% of all CVEs). NVD baseline CVSS 5.9 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Trending — 5 sources updated this weekElevated
5.9
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 87%
CISA-KEV: Not listedEPSS: 87%CVSS: 5.9Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

CVSS v3
5.9
EG Score
9.0(high)
EG Risk
—
EPSS
99.7%
KEV
Not listed

Published

January 20, 2021

Last Modified

November 4, 2025

References (15)

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntudnsmasq-utils (2.82-1ubuntu1.1) @ groovy2026-05-26ubuntu
redhatdnsmasq-0:2.79-13.el8_3.12021-01-19redhat
redhatdnsmasq-0:2.79-6.el8_1.12021-01-19redhat
redhatdnsmasq-0:2.79-11.el8_2.22021-01-19redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(5)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 8× in last 7d / 24× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 21:28 UTCEG score recompute▲ 3.10
  2. 2026-07-22 21:28 UTCVendor advisory
  3. 2026-07-22 21:28 UTCGHSA enrichment
  4. 2026-07-22 14:05 UTCEPSS rescore
  5. 2026-07-20 17:04 UTCEPSS rescore
  6. 2026-07-20 17:04 UTCEPSS rescore
  7. 2026-07-19 03:22 UTCOSV refresh
  8. 2026-07-16 16:59 UTCEPSS rescore
  9. 2026-07-15 01:57 UTCEPSS rescore
  10. 2026-07-13 06:10 UTCEPSS rescore
  11. 2026-07-13 06:10 UTCEPSS rescore
  12. 2026-07-12 05:44 UTCEPSS rescore
  13. 2026-07-04 06:29 UTCEPSS rescore
  14. 2026-07-04 06:28 UTCEPSS rescore
  15. 2026-07-01 10:18 UTCOSV refresh
  16. 2026-06-30 23:20 UTCEPSS rescore
  17. 2026-06-30 23:20 UTCEPSS rescore
  18. 2026-06-28 14:05 UTCEPSS rescore
  19. 2026-06-28 04:54 UTCEPSS rescore
  20. 2026-06-28 04:54 UTCEPSS rescore
  21. 2026-06-24 14:03 UTCEPSS rescore
  22. 2026-06-24 14:03 UTCEPSS rescore
  23. 2026-06-23 21:31 UTCEPSS rescore
  24. 2026-06-23 21:31 UTCEPSS rescore
  25. 2026-06-16 17:50 UTCEPSS rescore
Show 33 more
  1. 2026-06-16 17:50 UTCEPSS rescore
  2. 2026-06-15 17:46 UTCEPSS rescore
  3. 2026-06-14 23:15 UTCEPSS rescore
  4. 2026-06-13 22:58 UTCEPSS rescore
  5. 2026-06-13 22:58 UTCEPSS rescore
  6. 2026-06-13 15:43 UTCOSV refresh
  7. 2026-06-12 23:10 UTCEPSS rescore
  8. 2026-06-11 13:58 UTCEPSS rescore
  9. 2026-06-10 22:16 UTCEPSS rescore
  10. 2026-06-10 22:16 UTCEPSS rescore
  11. 2026-06-10 13:20 UTCEPSS rescore
  12. 2026-06-06 13:45 UTCEPSS rescore
  13. 2026-06-06 13:45 UTCEPSS rescore
  14. 2026-06-05 22:45 UTCEPSS rescore
  15. 2026-06-05 22:45 UTCEPSS rescore
  16. 2026-06-05 06:08 UTCEPSS rescore
  17. 2026-06-05 06:08 UTCEPSS rescore
  18. 2026-06-04 13:10 UTCEPSS rescore
  19. 2026-06-04 13:10 UTCEPSS rescore
  20. 2026-06-02 20:11 UTCEPSS rescore
  21. 2026-06-02 20:11 UTCEPSS rescore
  22. 2026-06-01 13:50 UTCEPSS rescore
  23. 2026-06-01 13:50 UTCEPSS rescore
  24. 2026-05-31 00:15 UTCEPSS rescore
  25. 2026-05-31 00:15 UTCEPSS rescore
  26. 2026-05-29 13:42 UTCEPSS rescore
  27. 2026-05-28 13:43 UTCEPSS rescore
  28. 2026-05-28 13:43 UTCEPSS rescore
  29. 2026-05-27 13:39 UTCEPSS rescore
  30. 2026-05-26 21:50 UTCEG score recompute
  31. 2026-05-26 21:50 UTCVendor advisory
  32. 2026-05-26 21:50 UTCGHSA enrichment
  33. 2026-05-24 16:48 UTCEPSS rescore

Frequently asked(5)

What is CVE-2020-25687?
CVE-2020-25687 is a medium vulnerability published on January 20, 2021. A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory.…
When was CVE-2020-25687 disclosed?
CVE-2020-25687 was first published in the National Vulnerability Database on January 20, 2021, with the most recent update on November 4, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-25687 actively exploited?
CVE-2020-25687 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-25687?
CVE-2020-25687 has a CVSS v3 base score of 5.9 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2020-25687?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-25687, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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