CVE-2026-16910: Quay: ssrf in red hat quay notification webhooks (slack/generic)
A flaw was found in Red Hat Quay's notification webhook dispatch feature. The SlackMethod and WebhookMethod notification handlers in notifications/notificationmethod.py accept attacker-controlled URLs without applying the validateexternalregistryurl() SSRF validator that protects other Quay features (proxy cache, organization mirror, repository mirror). A repository administrator can create a notification whose delivery URL points to internal network addresses. When the notification fires, the Quay worker performs a POST request to the attacker-specified URL, enabling blind SSRF from the worker network context. The WebhookMethod includes a HOSTNAMEBLACKLIST check, but it only performs exact-hostname matching against a minimal default list (localhost, 127.0.0.1) and is trivially bypassed with private IP literals, cloud metadata hostnames, or DNS rebinding.
Other sources
A flaw was found in Red Hat Quay's notification webhook feature. The Slack and generic webhook notification handlers accept user-supplied URLs without SSRF validation, allowing a repository administrator to make the Quay worker issue POST requests to internal network addresses or cloud infrastructure endpoints that should not be reachable from the application.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Update notifications/notificationmethod.py so SlackMethod and WebhookMethod handlers apply validate_external_registry_url() to attacker-supplied delivery URLs before dispatch; this SSRF validator is currently applied by other Quay features (proxy cache, organization mirror, repository mirror) but not these webhook handlers.
Red Hat Quay notification webhooks (Slack/generic) SSRF validation for webhook delivery URLs = validate external URLs using validate_external_registry_url() - Compensating control
Mitigate blind SSRF risk by restricting network egress from the Quay worker so it cannot reach internal network addresses, private IP ranges, or cloud metadata endpoints that the webhook delivery URL could target.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-16910?
CVE-2026-16910 has a medium severity rating of 5.5.
How do I fix CVE-2026-16910?
To mitigate CVE-2026-16910, update to the latest Red Hat Quay version that addresses this vulnerability.
What is the impact of CVE-2026-16910?
CVE-2026-16910 allows attackers to exploit SSRF by using unauthorized URLs in notification webhooks.
Is CVE-2026-16910 exploitable remotely?
Yes, CVE-2026-16910 is remotely exploitable due to its exposure over the network.
Which component of Red Hat Quay is affected by CVE-2026-16910?
CVE-2026-16910 affects the notification webhook dispatch feature in Red Hat Quay.