CVE detail
CVE-2026-33278
NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.
Buzz score
Why this CVE is surfacing
This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.
Buzz score components · mention 22.0 · diversity 18.0 · KEV 0.0 · OTX 0.0 · PoC 0.0
Why it matters now
Mention timeline
- Total mentions
- 0
- within the 30d window
- Peak daily
- 0
- highest bucket
Evidence
Source links by recency
8 source links · newest first
Information published.
vendormsrc.microsoft.comMay 21, 2026, 8:02 AM- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33278.jsonsecurity.access.redhat.com
No excerpt available.
Vendor Advisorysecurity.access.redhat.comMay 20, 2026, 10:16 AM - https://bugzilla.redhat.com/show_bug.cgi?id=2479808bugzilla.redhat.com
No excerpt available.
Exploitbugzilla.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/security/cve/CVE-2026-33278access.redhat.com
No excerpt available.
Vendor Advisoryaccess.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/errata/RHSA-2026:24369access.redhat.com
No excerpt available.
Vendor Advisoryaccess.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/errata/RHSA-2026:23231access.redhat.com
No excerpt available.
Vendor Advisoryaccess.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/errata/RHSA-2026:19752access.redhat.com
No excerpt available.
Vendor Advisoryaccess.redhat.comMay 20, 2026, 10:16 AM - https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txtwww.nlnetlabs.nl
No excerpt available.
Vendor Advisorywww.nlnetlabs.nlMay 20, 2026, 10:16 AM
Exploit code
Public exploit repository references
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0 repository references · best confidence N/A · max 0 stars
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