CVE-2026-25808
Published: 09 February 2026
Summary
CVE-2026-25808 is a high-severity Missing Authorization (CWE-862) vulnerability in Fedify Hollo. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 6.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requiring an access control policy ensures authorization checks are defined and applied for critical functions.
Reviews of access controls detect missing authorization checks on critical functions or resources.
Documenting permitted unauthenticated actions prevents missing authorization by making all exceptions explicit and subject to organizational review.
Requiring attribute association with information prevents authorization from being performed without necessary security or privacy context.
Mandating authorization prior to allowing remote connections addresses missing authorization for remote access.
Mandating authorization before wireless connections are allowed prevents missing authorization for wireless access.
The control requires authorization before allowing mobile device connections, directly mitigating missing authorization for system access.
Requiring approvals for account creation and specifying authorizations ensures authorization is not missing for system access.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Missing authorization on public ActivityPub outbox directly enables T1190 (exploit of internet-facing service) for unauthorized retrieval of local sensitive data (DMs/posts), mapping to T1005.
NVD Description
Hollo is a federated single-user microblogging software designed to be federated through ActivityPub. Prior to 0.6.20 and 0.7.2, there is a security vulnerability where DMs and followers-only posts were exposed through the ActivityPub outbox endpoint without authorization. This vulnerability is…
more
fixed in 0.6.20 and 0.7.2.
Deeper analysisAI
CVE-2026-25808 is a missing authorization vulnerability (CWE-862) in Hollo, a federated single-user microblogging software that integrates with ActivityPub for federation. In versions prior to 0.6.20 and 0.7.2, direct messages (DMs) and followers-only posts are exposed via the ActivityPub outbox endpoint without requiring proper authentication or authorization checks. The vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high confidentiality impact with no requirements for privileges or user interaction.
The issue allows unauthenticated remote attackers to access the outbox endpoint over the network, enabling them to retrieve sensitive content such as DMs and followers-only posts that should be restricted. Exploitation requires no special privileges, making it accessible to any internet-connected adversary who can reach the affected Hollo instance.
Mitigation is available through patches released for the affected versions: upgrade to Hollo 0.6.20 or 0.7.2, as detailed in the project releases and the specific commit fixing the authorization flaw. The GitHub security advisory GHSA-6r2w-3pcj-v4v5 provides further details on the issue and resolution.
Details
- CWE(s)