VulnerabilityPublished 1 Aug 2025

CVE-2025-54590: silverbucket webfinger.js · Server-Side Request Forgery (SSRF)

Affects silverbucket webfinger.jsSource CVE Database V5

Not known to be exploited · CVSS 6.9 Medium : upgrade to 2.8.1 when convenient.

Data as of 26 Oct 2026, 11:42 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.8.1

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 1 Aug 2025
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 silverbucket webfinger.js to 2.8.1.

Affected software

Product	Affected	Fixed in
silverbucket webfinger.js	Affected <2.8.1	Fixed in 2.8.1

AI-suggested

European organizations should immediately upgrade all instances of webfinger.js to version 2.8.1 or later, where the SSRF vulnerability is fixed by proper localhost and internal network access restrictions. Additionally, organizations should implement network-level controls such as firewall rules to restrict outbound HTTP requests from application servers to only necessary external endpoints, blocking internal IP ranges where possible. Application-level input validation should be enhanced to sanitize and whitelist acceptable hostnames and ports for WebFinger lookups, preventing attacker-controlled parameters from triggering SSRF. Monitoring and logging of outbound HTTP requests from services using webfinger.js should be enabled to detect anomalous or unexpected internal requests. For critical environments, consider deploying Web Application Firewalls (WAFs) with SSRF detection capabilities. Finally, conduct security reviews of all federated identity and ActivityPub-related components to ensure compliance with best practices and specifications, including strict localhost and internal network access prevention.

Description

webfinger.js is a TypeScript-based WebFinger client that runs in both browsers and Node.js environments. In versions 2.8.0 and below, the lookup function accepts user addresses for account checking. However, the ActivityPub specification requires preventing access to localhost services in production. This library does not prevent localhost access, only checking for hosts that start with "localhost" and end with a port. Users can exploit this by creating servers that send GET requests with controlled host, path, and port parameters to query services on the instance's host or local network, enabling blind SSRF attacks. This is fixed in version 2.8.1.

Impact

For European organizations using webfinger.js versions prior to 2.8.1, this SSRF vulnerability poses a risk of unauthorized internal network reconnaissance and potential access to sensitive internal services. Since webfinger.js is used in ActivityPub implementations, which are increasingly adopted in decentralized social networking and federated identity systems, exploitation could lead to leakage of internal metadata, unauthorized access to internal APIs, or pivoting to further internal attacks. The impact on confidentiality is moderate, as attackers can potentially access internal endpoints not exposed externally. Integrity and availability impacts are limited but could escalate if internal services are manipulated via SSRF. Given the lack of authentication or user interaction requirements, exploitation is relatively straightforward if the vulnerable library is exposed to attacker-controlled inputs. For European organizations, especially those involved in federated social platforms, identity management, or using Node.js-based services incorporating webfinger.js, this vulnerability could undermine trust and data privacy obligations under GDPR if internal data is exposed. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as the vulnerability is publicly disclosed.

CWE-918Server-Side Request Forgery (SSRF) (opens in a new tab)
Base weaknessCWE Top 25 (2025): #22OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.6.1 (opens in a new tab)
V5.2.6 (opens in a new tab)
Attack patterns
Server Side Request Forgery (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 1 Aug 2025, 18:33 UTC

WeaknessesCWE-918

Technical details

References

Community reviews

Related threats