PatchTheCVECVE-2026-56416: In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA form f
CVE-2026-56416 is a medium-severity flaw (CVSS 4.8) affecting unbound. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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 f
Why this priority
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 4.8 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.1% (top 98%) |
| CISA exploited list | No |
| Weakness | CWE-354 |
| Published | 2026-07-22 |
| Last modified | 2026-10-24 |
Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-56416?
unbound: upgrade to 1.25.2. Exact commands for each OS are on this page.
Is CVE-2026-56416 being exploited?
CVE-2026-56416 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-56416 affect?
CVE-2026-56416 affects unbound. Severity is medium (CVSS 4.8). 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(d
How urgent is CVE-2026-56416?
Priority 22/100. Remotely exploitable, no login, no user action
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