CVE-2025-32947 is a high-severity vulnerability affecting the PeerTube server, an open-source decentralized video hosting platform that uses the ActivityPub protocol for federated communication. The vulnerability is classified under CWE-835, which pertains to loops with unreachable exit conditions, commonly resulting in infinite loops. Specifically, this flaw exists in the handling of the "inbox" endpoint, which processes incoming ActivityPub activities. When the server receives specially crafted ActivityPub messages, it triggers an infinite loop, causing the PeerTube server to become unresponsive and stop processing legitimate requests. This denial-of-service (DoS) condition does not require any authentication or user interaction, making it remotely exploitable over the network with low complexity. The CVSS v3.1 base score is 7.5, reflecting a high impact on availability (A:H) while confidentiality and integrity remain unaffected (C:N/I:N). The vulnerability does not appear to have known exploits in the wild yet, and no patches have been linked at the time of publication. The infinite loop effectively halts the server’s ability to serve content or federate with other instances, severely disrupting service continuity and user experience.

For European organizations using PeerTube instances—particularly media outlets, educational institutions, and community platforms relying on decentralized video hosting—this vulnerability poses a significant risk of service disruption. An attacker can remotely trigger the infinite loop, causing downtime and potentially impacting the availability of critical video content and federated communication channels. This can degrade user trust and interrupt workflows dependent on PeerTube for content distribution. Since PeerTube is often used by privacy-conscious and decentralized communities, a successful DoS attack could also hinder efforts to provide censorship-resistant platforms. The lack of confidentiality or integrity impact limits data breach concerns; however, the availability impact alone can have operational and reputational consequences. Organizations with public-facing PeerTube servers are particularly vulnerable, as the attack requires no authentication or user interaction. Additionally, the federated nature of ActivityPub means that compromised instances could affect interconnected nodes, amplifying disruption within European federated networks.

Immediate mitigation involves monitoring and restricting incoming ActivityPub traffic to the "inbox" endpoint, potentially through rate limiting or filtering suspicious payloads at the network perimeter or application firewall. Administrators should implement strict validation of ActivityPub activities to detect and block malformed or suspicious messages before processing. Deploying Web Application Firewalls (WAFs) with custom rules targeting known exploit patterns can reduce exposure. Given the absence of official patches, organizations should consider temporarily disabling federation or restricting inbound federation traffic from untrusted peers until a fix is available. Regularly updating PeerTube to the latest versions once patches are released is critical. Additionally, implementing robust monitoring and alerting on server responsiveness and resource utilization can enable rapid detection of DoS attempts. Network segmentation and redundancy strategies can help maintain service continuity if one instance is targeted. Finally, engaging with the PeerTube community and security mailing lists will provide timely updates and shared mitigation strategies.