CVE detail
CVE-2026-44390
NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for this but it didn't account for the case where records would not share any suffix above the root. That causes Unbound to go in a different code path because of the compression tree lookup failure and eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch with a fix that increments the compression counter regardless of the compression tree lookup. This is a complement fix to CVE-2024-8508.
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 23.0 · 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
9 source links · newest first
- CVE-2026-44390 Unbounded name compression in certain cases causes degradation of serviceMicrosoft MSRC
Information published.
vendormsrc.microsoft.comMay 21, 2026, 8:03 AM - https://access.redhat.com/errata/RHSA-2026:37282access.redhat.com
No excerpt available.
Exploitaccess.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/errata/RHSA-2026:36777access.redhat.com
No excerpt available.
Exploitaccess.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/errata/RHSA-2026:36320access.redhat.com
No excerpt available.
Exploitaccess.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/errata/RHSA-2026:24013access.redhat.com
No excerpt available.
Exploitaccess.redhat.comMay 20, 2026, 10:16 AM - https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44390.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=2480130bugzilla.redhat.com
No excerpt available.
Exploitbugzilla.redhat.comMay 20, 2026, 10:16 AM - https://access.redhat.com/security/cve/CVE-2026-44390access.redhat.com
No excerpt available.
Exploitaccess.redhat.comMay 20, 2026, 10:16 AM - https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44390.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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