CVE-2026-16910
Description
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.
Statement
This Moderate flaw in Red Hat Quay's notification webhook dispatch allows an authenticated repository administrator to conduct blind Server-Side Request Forgery (SSRF). The Quay worker issues requests to attacker-specified URLs when notifications fire, but response data is not returned to the attacker, limiting exploitable impact to network probing and unauthenticated side-effects on internal services.
Mitigation
Restrict network egress from Quay worker pods/containers using network policies or firewall rules to block outbound connections to internal network ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) and cloud metadata endpoints (169.254.169.254). Limit repository creation and admin privileges to trusted users. Configure WEBHOOK_HOSTNAME_BLACKLIST in Quay config to include known internal hostnames and IP ranges.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 5.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | High | N/A | High |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Changed |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Integrity
Technical Impact: Execute Unauthorized Code or Commands
Access Control
Technical Impact: Bypass Protection Mechanism
By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
Acknowledgements
Red Hat would like to thank Martin Brodeur for reporting this issue.
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