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CVE Record

CVE-2020-25683: A flaw was found in dnsmasq before version 2.83.

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. A remote attacker, who can create valid DNS replies, could use this flaw 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 get_rdata() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2020-25683 is a dnsmasq flaw affecting versions before 2.83 when DNSSEC is enabled. A malicious or controlled DNS reply can trigger memory corruption before validation, causing dnsmasq to crash. The cited impact is denial of service, meaning DNS resolution may fail for affected systems or networks.

Executive priority

Treat this as a focused availability risk for DNS-dependent services. Patch affected dnsmasq deployments, especially DNSSEC-enabled resolvers and network appliances, but do not treat it as confirmed actively exploited based on the supplied sources.

Technical view

The flaw is a heap-based buffer overflow in dnsmasq's DNSSEC handling. Missing length checks in rfc1035.c:extract_name() can lead get_rdata() to call memcpy() with a negative size before DNS entries are validated. Sources describe the primary impact as availability loss through process crash.

Likely exposure

Exposure is most likely where dnsmasq before 2.83 is deployed with DNSSEC enabled, including Linux systems, appliances, routers, or embedded environments using dnsmasq for DNS forwarding or caching.

Exploitation context

The bundle does not indicate CISA KEV listing or active exploitation. Exploitation requires an attacker able to create valid DNS replies reaching the vulnerable dnsmasq instance. Public sources associate this with the Dnspooq disclosure set, but this CVE's cited impact is denial of service.

Researcher notes

Evidence supports a pre-validation DNSSEC parsing bug in dnsmasq before 2.83, CWE-122. The source bundle lacks CVSS details and does not prove code execution or active exploitation for this CVE. Validate exposure through version and DNSSEC configuration, then map fixes to vendor advisories.

Mitigation direction

  • Upgrade dnsmasq using vendor security updates or a fixed upstream release.
  • Prioritize systems running dnsmasq with DNSSEC enabled.
  • Follow Debian, Fedora, Gentoo, Red Hat, or device-vendor guidance for packaged fixes.
  • Where patching is delayed, review vendor guidance for DNSSEC-related risk reduction.
  • Track embedded and appliance firmware updates that bundle dnsmasq.

Validation and detection

  • Inventory dnsmasq versions across servers, network devices, containers, and firmware.
  • Confirm whether DNSSEC is enabled on each dnsmasq deployment.
  • Check package manager advisory status against the listed vendor updates.
  • Review service logs for unexplained dnsmasq crashes or restart loops.
  • Validate patched systems continue providing expected DNS resolution.
Prepared
Confidence
high
Sources
7

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-122: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2020-25683 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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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
9Source 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/adnsmasqdnsmasq 2.83Listed
Weakness

CWE details

CWE-122

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

CWE-122 · source CWE mapping

Heap-based Buffer Overflow

Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs