Dnsmasq: dnsmasq: out-of-bailiwick cache injection through cname chase in split-dns configurations
Summary
| CVE | CVE-2026-93008 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-29 13:17:16 UTC |
| Updated | 2026-11-05 01:17:24 UTC |
| Description | A flaw was found in dnsmasq. When following a CNAME in a DNS response, the resolver can cache records for the CNAME target without checking that those records belong to the responding server's authorized zone. In split-DNS deployments that send some domains to a specific upstream, an attacker who controls that upstream can inject cache entries for unrelated names. Later clients may then receive attacker-chosen addresses for those names. |
Risk And Classification
Primary CVSS: v3.1 6.8 MEDIUM from [email protected]
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N
EPSS: 0.001500000 probability, percentile 0.041580000 (date 2026-11-03)
Problem Types: CWE-345 | CWE-345 Insufficient Verification of Data Authenticity
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 6.8 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N |
| 3.1 | CNA | CVSS | 6.8 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| access.redhat.com/security/cve/CVE-2026-93008 | [email protected] | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-09-14T00:00:00.000Z | Reported to Red Hat. |
| CNA | 2026-10-28T09:32:00.000Z | Made public. |
Workarounds
CNA: The following measures reduce risk: 1. Do not point server=/domain/ at untrusted or attacker-reachable DNS servers. 2. Restrict dnsmasq to communicate only with trusted upstream resolvers at the firewall. 3. For local=/domain/ zones, define all names that should be served locally. 4. Do not rely on --dnssec to mitigate this for unsigned zones. Insecure records are still cached.