GHSA-v2gc-rm6g-wrw9: craftcms/cms (CVE-2026-27129)

Package	Ecosystem	Affected	Fixed in
craftcms/cms	Packagist	>=5.0.0-RC1, <5.8.23 \|\| >=3.5.0, <4.16.19	5.8.23, 4.16.19

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Craft CMS versions >=3.5.0 before 4.16.19, and >=5.0.0-RC1 before 5.8.23, are vulnerable to an SSRF protection bypass in the GraphQL Asset mutation. An attacker with edit and create permissions on an asset volume (which may be granted to authenticated users or the public schema if misconfigured) can use hostnames that resolve only to IPv6 addresses to reach blocked internal targets, such as cloud metadata services. Upgrade to 4.16.19 or 5.8.23.

Written 3 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
5.7	Medium	4.0	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0047, the 41st percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:26 UTC First seen by agentprime
31 Oct 2026, 14:26 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.