VDB-349499 · CVE-2026-26017 · GHSA-c9v3-4pv7-87pr

CoreDNS up to 1.14.1 Security Plugin toctou

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.9	$0-$5k	0.00

Summaryinfo

A vulnerability has been found in CoreDNS up to 1.14.1 and classified as problematic. The impacted element is an unknown function of the component Security Plugin Handler. The manipulation leads to toctou. This vulnerability is traded as CVE-2026-26017. It is possible to initiate the attack remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in CoreDNS up to 1.14.1. This issue affects an unknown part of the component Security Plugin Handler. The manipulation with an unknown input leads to a toctou vulnerability. Using CWE to declare the problem leads to CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. Impacted is confidentiality. The summary by CVE is:

CoreDNS is a DNS server that chains plugins. Prior to version 1.14.2, a logical vulnerability in CoreDNS allows DNS access controls to be bypassed due to the default execution order of plugins. Security plugins such as acl are evaluated before the rewrite plugin, resulting in a Time-of-Check Time-of-Use (TOCTOU) flaw. This issue has been patched in version 1.14.2.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-26017 since 02/09/2026. The exploitation is known to be easy. The attack may be initiated remotely. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 1.14.2 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0627). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

Open Source CoreDNS

Productinfo

Name

CoreDNS

Version

Website

Product: https://github.com/coredns/coredns/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.0
VulDB Meta Temp Score: 5.9

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.7
CNA Vector (GitHub_M): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Toctou
CWE: CWE-367 / CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: CoreDNS 1.14.2

Timelineinfo

02/09/2026 CVE reserved
03/06/2026 +25 days Advisory disclosed
03/06/2026 +0 days VulDB entry created
03/08/2026 +2 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-c9v3-4pv7-87pr
Status: Confirmed

CVE: CVE-2026-26017 (🔒)
GCVE (CVE): GCVE-0-2026-26017
GCVE (VulDB): GCVE-100-349499
CERT Bund: WID-SEC-2026-0627 - CoreDNS: Mehrere Schwachstellen

Entryinfo

Created: 03/06/2026 17:31
Updated: 03/08/2026 21:02
Changes: 03/06/2026 17:31 (64), 03/08/2026 21:02 (7)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.