CVE-2026-56416
CVE-2026-56416: 1 tracked advisory record across Red Hat. Compare source-reported impact, fixes and remediation.
Compare the source-linked records below. Ratings and product/version details belong to each advisory; they are not a single CVE-wide score or proof that every listed product is affected. How VulniPulse collects and checks evidence.
Vendor advisory comparison
Red Hat
1 advisory- Advisory severityMedium4.8
Medium [CVE-2026-56416] Heap buffer overflow via malformed DNSSEC record
CVE-2026-56416Source published Source updated
In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA form for an RRSIG-covered PX/RP/MINFO/SOA RRset, it computes the address of the second embedded domain name as 'datstart + dname_valid(datstart,...)' and passes it straight to 'query_dname_tolower()' without checking that a second name is actually present in the RDATA. The wire-format parser accepts multi-dname RRs whose RDATA ends after the first name, so an attacker who runs a DNSSEC-signed authoritative server can deliver a record with an absent second domain name (e.g. SOA record) and cause 'query_dname_tolower()' to walk label-by-label through stale bytes in the per-worker 'env->scratch_buffer', past the end of that heap allocation if 'msg-buffer-size' has been lowered from the…
- Affected products in this advisory
- Red Hat Hardened Images
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
4 more entries in the full advisory.
- Source-reported affected versions
- 1.25.1
- Source-reported fixed versions
- unbound-main-1.25.2-0.1.hum1
- RHSA-2026:43588
- Mitigation guidance
- To mitigate this issue, consider disabling DNSSEC validation in Unbound if it is not strictly required for your environment. This can be achieved by ensuring `module-config: "iterator"` is used in `unbound.conf` and that no `trust-anchor` or `auto-trust-anchor-file` directives are present. Disabling DNSSEC validation will reduce the security assurances provided by DNSSEC. Alternatively, configure Unbound to only perform DNSSEC validation for trusted zones. A restart of the Unbound service is required for changes to take effect.
Android app · Google Play
Monitor future Red Hat CVEs from your phone.
Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 32 official vendor sources and 160+ reviewed platform categories.