CVE-2026-27127
Craft is a content management system (CMS). In versions 4.5.0-RC1 through 4.16.18 and 5.0.0-RC1 through 5.8.22, the SSRF validation in Craft CMS’s GraphQL Asset mutation performs DNS resolution separately from the HTTP request. This Time-of-Check-Time-of-Use (TOCTOU) vulnerability enables DNS rebinding attacks, where an attacker’s DNS server returns different IP addresses for validation compared to the actual request. This is a bypass of the security fix for CVE-2025-68437 that allows access to all blocked IPs, not just IPv6 endpoints. Exploitation requires GraphQL schema permissions for editing assets in the <VolumeName> volume and creating assets in the <VolumeName> volume. These permissions may be granted to authenticated users with appropriate GraphQL schema access and/or Public Schema (if misconfigured with write permissions). Versions 4.16.19 and 5.8.23 patch the issue.
| Software | From | Fixed in |
|---|---|---|
| craftcms / craft_cms | 3.5.1 | 4.16.19 |
| craftcms / craft_cms | 5.0.1 | 5.8.23 |
| craftcms / craft_cms | 3.5.0 | 3.5.0.x |
| craftcms / craft_cms | 5.0.0 | 5.0.0.x |
| craftcms / craft_cms | 5.0.0-rc1 | 5.0.0-rc1.x |
craftcms / cms
|
5.0.0-RC1 | 5.8.23 |
|
craftcms / cms
|
3.5.0 | 4.16.19 |
- https://curl.se/libcurl/c/CURLOPT_RESOLVE.html
- https://github.com/craftcms/cms/commit/a4cf3fb63bba3249cf1e2882b18a2d29e77a8575
- https://github.com/craftcms/cms/security/advisories/GHSA-gp2f-7wcm-5fhx
- https://github.com/craftcms/cms/security/advisories/GHSA-x27p-wfqw-hfcc
- https://github.com/mogwailabs/DNSrebinder
- https://github.com/nccgroup/singularity
- https://github.com/taviso/rbndr
- https://unit42.paloaltonetworks.com/dns-rebinding
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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
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