TI-2026-57038 Aliases CVE-2026-82717 GHSA-r5xg-xh8m-9q2w

CNAME synthesis could lead to heap corruption

MEDIUM 40CWE-122Published 2026-09-16 · Updated 2026-09-16

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Attack requirements: None
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: Partial Red Hat: 7 fixed, 4 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-122 and the CVSS impact.

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 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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00782 56th percentileScored 2026-11-07

Fix Partial Unbound (NLnet Labs): 1.26.1Red Hat: 5 advisoriesRed Hat: 7 fixed, 4 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

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 1.26.1	1.26.1	Patch available	CNA

Unbound VendorNLnet Labs Affected before 1.26.1 Fixed in 1.26.1 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:nlnetlabs:unbound::::::::	before 1.26.1	Vulnerable	NLNETLABS

cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:* Versions before 1.26.1 Vulnerable ·NLNETLABS

Remediation

Fix · CNA Unbound (NLnet Labs) Fixed in 1.26.1

Red Hat 5 advisories

RHSA-2026:74428 Released 2026-10-06 · Red Hat rating Important
OpenShift Container Platform 4.22.17 bug fix and security update
- Red Hat OpenShift Container Platform 4.22 rhcos-aarch64-4.22.9.8.202609291947-0, rhcos-ppc64le-4.22.9.8.202609291947-0, rhcos-s390x-4.22.9.8.202609291947-0 +1
RHSA-2026:71487 Released 2026-09-24 · Red Hat rating Critical
unbound security update
- Red Hat Enterprise Linux AppStream (v. 9) python3-unbound-1.24.2-3.el9_8.8, unbound-1.24.2-3.el9_8.8, unbound-dracut-1.24.2-3.el9_8.8 +1
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) unbound-devel-1.24.2-3.el9_8.8
RHSA-2026:71419 Released 2026-09-24 · Red Hat rating Critical
unbound security update
- Red Hat Enterprise Linux AppStream (v. 10) python3-unbound-1.24.2-7.el10_2.6, unbound-1.24.2-7.el10_2.6, unbound-anchor-1.24.2-7.el10_2.6 +3
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) unbound-devel-1.24.2-7.el10_2.6

Show 2 more Red Hat advisories

RHSA-2026:70754 Released 2026-09-23 · Red Hat rating Critical
unbound security update
- Red Hat Enterprise Linux AppStream (v. 8) python3-unbound-1.16.2-5.14.el8_10.4, unbound-1.16.2-5.14.el8_10.4, unbound-devel-1.16.2-5.14.el8_10.4 +1
RHSA-2026:68590 Released 2026-09-17 · Red Hat rating Critical
Red Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images python3-unbound-1.26.1-1.hum1@aarch64, python3-unbound-1.26.1-1.hum1@x86_64, unbound-1.26.1-1.hum1@aarch64 +14

Fixed in the same release

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

Release · 2026-09-16
NLnet Labs Unbound 1.26.1
9 records Highest priority Priority MEDIUM 2 MEDIUM, 7 LOW
Other records, highest priority first
- TI-2026-56302 Heap buffer overflow and possible Remote Code Execution when digesting DNSKEYPriority MEDIUM 49
- TI-2026-58665 Retrap: Novel Vulnerabilities to launch Algorithmic Complexity Attacks on DNSSECPriority LOW 39
- TI-2026-56296 Possible heap buffer overflow during DNSSEC canonicalizationPriority LOW 39
Show all 9 records →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux 6	Affected	No fix planned: Out of support scope
Red Hat Enterprise Linux 7	Affected	No fix yet
Red Hat OpenShift Container Platform 4	Affected	No fix yet
Red Hat OpenShift Container Platform 5	Affected	No fix yet
Red Hat Enterprise Linux AppStream (v. 10)	Fixed	RHSA-2026:71419
Red Hat Enterprise Linux AppStream (v. 8)	Fixed	RHSA-2026:70754
Red Hat Enterprise Linux AppStream (v. 9)	Fixed	RHSA-2026:71487
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)	Fixed	RHSA-2026:71419
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)	Fixed	RHSA-2026:71487
Red Hat Hardened Images	Fixed	RHSA-2026:68590
Red Hat OpenShift Container Platform 4.22	Fixed	RHSA-2026:74428

Timeline

2026-10-02 Threatist record created from CVE-2026-82717
2026-10-03 Alias added: GHSA-r5xg-xh8m-9q2w
2026-10-07 Fix available: RHSA-2026:74428 · Red Hat
2026-10-07 Fix available: Red Hat OpenShift Container Platform 4.22 · Red Hat
2026-10-30 Affected versions changed · Red Hat

References

Patch 1

https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-82717.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