dnsmasq: Out-of-bounds Read
CVE-2026-5172 is a high-severity out-of-bounds read vulnerability in dnsmasq, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 2.92rel2 as the first without the flaw, so updating dnsmasq to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 2.68% chance of exploitation within 30 days, higher than 86% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update dnsmasq to 2.92rel2 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Dnsmasq | dnsmasq | before 2.92rel2 | 2.92rel2 |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4 | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.3 | High | CISA (ADP) |
| CVSS 3.1 | 7.5 | High | CNA |
Official description
A buffer overflow in dnsmasq’s extract_addresses() function allows an attacker to trigger a heap out-of-bounds read and crash by exploiting a malformed DNS response, enabling extract_name() to advance the pointer past the record’s end.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
- lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html
- thekelleys.org.uk/dnsmasq/CVE/
- kb.cert.org/vuls/id/471747
- access.redhat.com/errata/RHSA-2026:19158
- access.redhat.com/security/cve/CVE-2026-5172
- bugzilla.redhat.com/show_bug.cgi?id=2458521
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5172.json
Other vulnerabilities in dnsmasq
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Out-of-bounds Read vulnerabilities
- 7.7 High severity
- 7.3 High severity
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
- 7.5 High severity
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