VulnerabilityPublished 9 Feb 2026

CVE-2026-25808: fedify-dev hollo · Missing Authorization

Affects fedify-dev holloSource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 0.7.2 soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.7.2

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade fedify-dev hollo to 0.7.2.

Affected software

Product	Affected	Fixed in
fedify-devhollo	Affected >=7.0.0 <0.7.2	Fixed in 0.7.2

AI-suggested

Immediately upgrade all Hollo instances to version 0.6.20 or 0.7.2 or later, where the authorization flaw is fixed.
Audit existing ActivityPub outbox endpoint configurations to ensure proper access controls are enforced, restricting content visibility to authorized followers only.
Implement network-level monitoring and logging to detect unusual access patterns to the outbox endpoint, which may indicate exploitation attempts.
Educate users and administrators about the sensitivity of direct messages and followers-only posts, encouraging cautious sharing until patches are applied.
Consider deploying Web Application Firewalls (WAFs) with custom rules to block unauthorized requests targeting the outbox endpoint as an interim protective measure.
Review federation partner configurations to ensure they do not inadvertently expose private data through federation protocols.
Establish incident response procedures to quickly address any detected unauthorized data access. 8.

Description

CVE-2026-25808 is a high-severity vulnerability in Hollo, a federated microblogging platform using ActivityPub. Versions prior to 0.6.20 and 0.7.2 improperly expose direct messages and followers-only posts via the ActivityPub outbox endpoint without requiring authorization. This results in unauthorized disclosure of private communications and restricted content. The vulnerability does not require authentication or user interaction and can be exploited remotely over the network. It affects confidentiality but not integrity or availability. The issue is fixed in versions 0.

Impact

For European organizations, this vulnerability threatens the confidentiality of private communications within Hollo instances, potentially exposing sensitive direct messages and followers-only content to unauthorized external parties. This could lead to privacy violations, reputational damage, and regulatory non-compliance, especially under GDPR requirements concerning personal data protection. Organizations using Hollo for internal or community communications may inadvertently leak confidential information, undermining trust and operational security. The federated nature of Hollo increases the attack surface, as malicious actors can remotely query vulnerable endpoints without authentication. While integrity and availability remain unaffected, the breach of confidentiality alone is critical given the sensitivity of direct messages. The impact is particularly severe for sectors handling sensitive data such as government agencies, NGOs, and enterprises relying on federated social platforms for communication. The lack of known exploits in the wild suggests a window of opportunity for proactive mitigation before widespread abuse occurs.

CWE-862Missing Authorization (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #4OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
Architecture and Design
Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
Architecture and Design
Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
V7.2.2 (opens in a new tab)
Attack patterns
Exploitation of Thunderbolt Protection Flaws (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Feb 2026, 09:30 UTC

WeaknessesCWE-862

Technical details

References

Community reviews

Related threats