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CVE Record

CVE-2021-45955: Dnsmasq 2.86 has a heap-based buffer overflow in resize_packet (called from FuzzResizePacket and fuzz_rfc10...

Dnsmasq 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 bounds check upon pseudo header re-insertion. 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." However, a contributor states that a security patch (mentioned in 016162.html) is needed

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-45955 concerns a reported heap buffer overflow in Dnsmasq 2.86. The issue is disputed by the vendor, who said this CVE group does not represent real vulnerabilities to their knowledge, while another contributor said a security patch is needed.

Executive priority

Monitor and validate rather than emergency response. Prioritize if Dnsmasq 2.86 is exposed in critical DNS or DHCP infrastructure, but current public evidence does not confirm exploitation or severity.

Technical view

The report describes a heap-based buffer overflow in resize_packet during pseudo-header re-insertion, identified through fuzzing references. Public metadata does not provide CVSS, confirmed affected package ranges, exploitability details, or a definitive fixed release. Treat it as an uncertain memory-safety finding requiring vendor and distribution confirmation.

Likely exposure

Potential exposure is limited to environments running Dnsmasq 2.86 or packages carrying the relevant code path. The supplied CVE record does not identify CPEs, distributions, appliances, or downstream package status.

Exploitation context

The source bundle does not show CISA KEV listing, active exploitation, public exploit use, or confirmed real-world impact. Evidence is fuzzing-based and disputed by the vendor.

Researcher notes

The main uncertainty is exploitability. The CVE description alleges a heap overflow, but vendor commentary disputes that the related CVEs are real vulnerabilities. Research should focus on reproducing the fuzz finding safely and mapping downstream patches.

Mitigation direction

  • Inventory systems and appliances running Dnsmasq 2.86.
  • Check Dnsmasq and distribution advisories for this CVE and related patch status.
  • Apply maintainer-provided Dnsmasq updates if they address the reported bounds issue.
  • Track the linked dnsmasq-discuss threads for vendor and contributor clarification.

Validation and detection

  • Confirm installed Dnsmasq versions across servers, routers, and embedded images.
  • Review package changelogs for CVE-2021-45955 or the related security patch discussion.
  • Check whether local builds include changes around resize_packet pseudo-header handling.
  • Document any exposed Dnsmasq instances pending maintainer clarification.
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-2021-45955 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.