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TI-2021-20958 Aliases CVE-2021-45955GHSA-p5g5-mjp3-mr9m

Dnsmasq 2.86 has a heap-based buffer overflow in resize_packet (called from…

Priority HIGH 82CWE-787Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-787 and the CVSS impact.

Summary

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

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.02602 85th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:thekelleys:dnsmasq:2.86:*:*:*:*:*:*:*2.86VulnerableThekelleys
  • cpe:2.3:a:thekelleys:dnsmasq:2.86:*:*:*:*:*:*:* Versions 2.86 Vulnerable ·Thekelleys

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 5 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat OpenStack Platform 13 (Queens)

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-45955
  2. 2026-10-03 Alias added: GHSA-p5g5-mjp3-mr9m

References

Exploit 1

Advisory 3

  • TI-2017-10595 Heap-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a… CVSS 3.0CRITICAL 9.8
  • TI-2023-27571 Certain DNSSEC aspects of the DNS protocol (in RFC 4033, 4034, 4035, 6840, and related… CVSS 3.1HIGH 7.5
  • TI-2017-10596 Stack-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a… CVSS 3.0CRITICAL 9.8
  • TI-2017-10594 Heap-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a… CVSS 3.1CRITICAL 9.8
  • TI-2020-15697 Heap-based buffer overflow in dnsmasq CVSS 3.1HIGH 8.1
  • TI-2020-15698 Heap-based buffer overflow in dnsmasq CVSS 3.1HIGH 8.1
See all 38 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences