TI-2026-78584 Aliases CVE-2026-96405 GHSA-r7j4-9v27-x32x

Unbound resolver lacks aggregate limit on DNS compression pointers

LOW 30CWE-770Published 2026-10-21 · Updated 2026-10-29

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · Low
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-770.

Summary

NLnet Labs Unbound before 1.26.2 has no aggregate budget for the work needed to decompress DNS names in a message. Many chained compression pointers in one message make the resolver use a lot of CPU when it follows them (CWE-770). An attacker with recursive query access who controls a delegated authority that serves crafted replies can degrade Unbound's general performance.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

NLnet Labs Unbound up to and including version 1.26.1 limits compression-pointer traversal for each individual domain-name operation but has no aggregate inbound decompression-work budget. Many chained compression pointers in a message results in a lot of CPU usage following them. A malicious actor with recursive-query access and control of an ordinarily delegated authority that serves specially crafted replies can exploit the vulnerability and degrade Unbound's general performance.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00254 16th percentileScored 2026-11-07

Fix Fixed Unbound (NLnet Labs): 1.26.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
NLnet Labs	Unbound	before 1.26.2	1.26.2	Patch available	CNA

Unbound VendorNLnet Labs Affected before 1.26.2 Fixed in 1.26.2 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:nlnetlabs:unbound::::::::	—	—	NLNETLABS

cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:* Versions — — ·NLNETLABS

Remediation

Upgrade NLnet Labs Unbound to version 1.26.2.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Fix · CNA Unbound (NLnet Labs) Fixed in 1.26.2

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-10-21
NLnet Labs Unbound 1.26.2
5 records Highest priority Priority LOW 5 LOW
Other records, highest priority first
- TI-2026-78586 Unbound DoQ path migration use-after-free on multi-threaded deploymentsPriority LOW 39
- TI-2026-78546 Unbound NXDOMAIN denial for island trust anchor under insecure parentPriority LOW 28
- TI-2026-78614 Cache side-channel in NLnet Labs Unbound leaks upstream source portPriority LOW 23
Show all 5 records →

Timeline

2026-10-21 Threatist record created from CVE-2026-96405
2026-10-21 Alias added: GHSA-r7j4-9v27-x32x
2026-10-29 CISA SSVC decision points changed

References

Advisory 1

https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-96405.txt

TI-2026-25690 Possible arbitrary code execution during DNSSEC validation CVSS 4.0CRITICAL 9.1
TI-2026-56302 Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY CVSS 4.0CRITICAL 9.1
TI-2026-31146 Crash during DNSSEC validation of malicious content CVSS 4.0HIGH 8.7
TI-2026-31135 Heap overflow with multiple NSID, COOKIE, PADDING EDNS options CVSS 4.0HIGH 8.7
TI-2026-36436 Routinator crashes on specifically crafted RRDP XML files CVSS 4.0HIGH 8.7
TI-2026-36433 Routinator exits when accepting an incoming HTTP or RTR connection fails CVSS 4.0HIGH 8.7

See all 96 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences