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CVE Record

CVE-2021-45951: Dnsmasq 2.86 has a heap-based buffer overflow in check_bad_address (called from check_for_bogus_wildcard an...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-45951 is reported as a heap-based buffer overflow in dnsmasq 2.86. The important caveat is that the vendor publicly stated this CVE group does not represent real vulnerabilities, to the best of its knowledge. Treat it as a disputed finding, not a confirmed emergency.

Executive priority

Moderate operational follow-up, low emergency signal. Security teams should validate inventory and scanner output, but the current source bundle does not justify incident response escalation.

Technical view

The record describes a heap-based buffer overflow in dnsmasq 2.86 within check_bad_address, reached from check_for_bogus_wildcard and an OSS-Fuzz harness. No CVSS score, CWE, confirmed affected CPEs, patch, or exploitation evidence is provided in the supplied sources. The vendor disputes vulnerability status.

Likely exposure

Potential exposure is limited to environments running dnsmasq 2.86, but the source bundle does not confirm exploitable product impact or affected configurations. Routers, appliances, Linux servers, containers, and embedded systems may include dnsmasq, so version inventory matters.

Exploitation context

The supplied evidence does not show active exploitation, public weaponization, or inclusion in CISA KEV. The origin appears fuzzing-related, and the vendor’s stated position materially weakens confidence that this is a practical vulnerability.

Researcher notes

Key uncertainty is exploitability. The description names a memory-safety condition, but the vendor disputes real vulnerability status and the supplied data lacks reproducibility, affected CPEs, CVSS, or remediation details. Avoid overstating impact.

Mitigation direction

  • Inventory dnsmasq deployments and identify any version 2.86 instances.
  • Check dnsmasq vendor and Linux distribution advisories for authoritative guidance.
  • Do not assume emergency remediation without confirming product impact.
  • Keep dnsmasq updated through supported vendor or distribution packages.
  • Monitor CVE, vendor, and KEV updates for any status change.

Validation and detection

  • Confirm installed dnsmasq versions across servers, appliances, images, and embedded devices.
  • Compare scanner findings against vendor and distribution advisory status.
  • Document whether dnsmasq is internet-facing or only locally reachable.
  • Review change records for package updates after December 31, 2021.
  • Track whether the CVE remains disputed in vulnerability management tooling.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-45951 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.