CVE-2026-123201
Description
A flaw was found in buku. This vulnerability allows an unauthenticated remote attacker to cause information disclosure through Server-Side Request Forgery (SSRF) due to improper URL validation in the bukuserver component. By supplying crafted web addresses to API endpoints, an attacker can coerce the server into sending requests to internal network resources, loopback addresses, or cloud metadata services to discover services and retrieve sensitive data.
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Mitigation
Restrict network reachability to the web server daemon or disable the web interface:
1. If the web UI is not strictly required, stop the bukuserver process and manage bookmarks solely through the command-line interface. If managed as a system service:
# systemctl stop bukuserver
# systemctl disable bukuserver
2. If the web interface must remain active, ensure bukuserver binds strictly to the loopback address (127.0.0.1) rather than public interfaces, and block external network traffic to the service port (default 5001/tcp) using firewalld:
# firewall-cmd --permanent --remove-port=5001/tcp
# firewall-cmd --reload
Caveat: Disabling the service or blocking the port prevents remote web access to bookmark management. Warning: Reloading firewalld immediately refreshes active firewall rules and terminates external sessions.
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.
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