CVEFinder.io

CVE-2026-82717

⛔ critical
Summary

In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in that can progressively corrupt heap memory and under certain systems and compilation options could lead to remote code execution. The vulnerability starts when CNAME synthesis during an upstream response needs to enforce(rewrite) a max TTL value in the packet buffer. Coupled with a compression pointer that points to the overwritten value and invalidates the domain name, it leads to an error path that does not properly

Description

In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in that can progressively corrupt heap memory and under certain systems and compilation options could lead to remote code execution. The vulnerability starts when CNAME synthesis during an upstream response needs to enforce(rewrite) a max TTL value in the packet buffer. Coupled with a compression pointer that points to the overwritten value and invalidates the domain name, it leads to an error path that does not properly move the buffer position and allows for the heap buffer overflow. Since this is heavily reliant on heap memory layout, results are memory corruption that eventually leads to a crash and under specific systems and compilation options remote code execution.

CVSS Score
9.8
Critical
EPSS Score
0.8
Exploit Probability
Published Date
2026-09-16
First Seen: 2026-09-18
📊 Relative Risk Intelligence

This CVE is Very High Risk - more severe than 90.6% of all 365,968 vulnerabilities in our database.

#34,458
Top 10% most severe
Severity Percentile
đŸŽ¯ CISA SSVC Assessment Updated: Sep 16, 2026
🔍 Exploitation Status
None
No known exploits
⚙ī¸ Automatable
NO
Requires human interaction
đŸ’Ĩ Technical Impact
Total
Complete system compromise possible
🏆 Discovered By
Ben Morris (Anthropic)
SSVC data provided by CISA
Last Modified 2026-09-23
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Vector 4.0 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE IDs (Weakness Types)
CWE-122

đŸ“Ļ Affected Products 1

Vendor Product Status Affected Versions
nlnetlabs unbound Affected
< 1.26.1

🔗 References 1

https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-...
Patch Vendor Advisory

🔗 Related CVEs 6

CVE ID Severity CVSS EPSS Summary Published
CVE-2026-77860 ℹī¸ low 3.7 0.3 In NLnetLabs Unbound 1.20.0 up to and including 1.26.0, a vulnerability on the 'serve-expired' code path can cause a dou... 2026-09-16
CVE-2026-77955 đŸ”ļ medium 4.4 0.2 In NLnet Labs Unbound 1.13.2 up to and including 1.26.1, a vulnerability in ZONEMD configured zones (zonemd-check: yes) ... 2026-09-16
CVE-2026-78227 đŸ”ļ medium 6.5 0.3 NLnet Labs Unbound 1.22.0 up to and including 1.26.1, has a use-after-free vulnerability when compiled for DNS-over-QUIC... 2026-09-16
CVE-2026-80225 đŸ”ļ medium 5.3 0.5 In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the TCP/DoT readin... 2026-09-16
CVE-2026-81634 ⚠ī¸ high 7.5 0.5 In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can lead to a heap b... 2026-09-16
CVE-2026-81642 ⛔ critical 9.8 1.0 In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in the DNSSEC validator that enables denial ... 2026-09-16
These CVEs affect the same products