Security readout for executives and security teams
Plain-English summary
CVE-2026-5172 is a dnsmasq crash vulnerability. A malformed DNS response can make dnsmasq read beyond a heap buffer and terminate, disrupting DNS service. The business impact is availability: affected DNS forwarders can fail without authentication or user interaction.
Executive priority
Treat this as a high-priority availability issue for DNS infrastructure. Prioritize internet-facing, shared, or business-critical dnsmasq deployments, especially where DNS outage would interrupt authentication, service discovery, or customer-facing systems.
Technical view
The issue is in dnsmasq extract_addresses(). A malformed DNS response can cause extract_name() to advance a parsing pointer past the record end, leading to a heap out-of-bounds read and crash. The provided CVSS is 7.5, network exploitable, low complexity, unauthenticated, with high availability impact only.
Likely exposure
Exposure is likely wherever dnsmasq processes DNS responses from untrusted or attacker-influenced sources. The bundle does not provide a precise affected version range, so teams should rely on vendor package advisories for applicability.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The described attack path is remote and unauthenticated, but the documented outcome is service crash rather than data theft or code execution.
Researcher notes
The bundle supports a denial-of-service conclusion from heap out-of-bounds read behavior. It does not support active exploitation, code execution, confidentiality impact, or a universal affected version range. Vendor-specific packaging evidence should drive final exposure decisions.
Mitigation direction
- Review dnsmasq upstream CVE guidance for affected versions and fixes.
- Apply relevant vendor updates, including distro advisories such as Red Hat RHSA-2026:19158.
- Review Pi-hole FTL v6.6.2 guidance if using Pi-hole-provided dnsmasq components.
- Track NixOS advisory or package updates if using nixpkgs builds.
- Restrict DNS service exposure where operationally possible.
Validation and detection
- Inventory hosts, containers, and appliances running dnsmasq.
- Compare installed dnsmasq packages against vendor advisory status.
- Confirm whether DNS responses can originate from untrusted networks.
- Verify patched package or vendor release installation after remediation.
- Monitor dnsmasq crash logs and service restarts for suspicious malformed-response activity.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-125: 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 lookupCWE-787: 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 lookupCVE-2026-5172 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L3.93.4CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Reported to Red Hat.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-04-14T22:55:28.042Z: Reported to Red Hat.
- 2026-05-09T00:00:00.000Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.kb.cert.org/vuls/id/471747CVE reference, certcc
- https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.htmlCVE reference, certcc
- https://thekelleys.org.uk/dnsmasq/CVE/CVE reference, certcc
- https://github.com/NixOS/nixpkgs/pull/519082CVE reference, certcc
- https://github.com/NixOS/nixpkgs/pull/519093CVE reference, certcc
- https://github.com/pi-hole/FTL/releases/tag/v6.6.2CVE reference, certcc
- https://access.redhat.com/security/cve/CVE-2026-5172CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2458521CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5172.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:19158CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.