VulnerabilityPublished 10 Jun 2026

CVE-2026-50131: fedify · Server-Side Request Forgery (SSRF)

Affects fedifySource CVE Database V5

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Not known to be exploited · CVSS 8.6 High · fixed in 2.2.4 : patch fedify soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

8.6High

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.2.4, 2.1.15, 2.0.19 +2

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

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

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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
fedify-devfedify	Affected >=2.2.0 <2.2.4	Fixed in 2.2.4
fedify-devfedify	Affected >=2.1.0 <2.1.15	Fixed in 2.1.15
fedify-devfedify	Affected >=2.0.0 <2.0.19	Fixed in 2.0.19
fedify-devfedify	Affected >=1.10.0 <1.10.11	Fixed in 1.10.11
fedify-devfedify	Affected >=0.11.2 <1.9.12	Fixed in 1.9.12
fedify-devvocab-runtime	Affected >=2.2.0 <2.2.4	Fixed in 2.2.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Updated patched versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 contain fixes for the incomplete IPv4 validation logic and should be applied to remediate this vulnerability. Since no official vendor advisory or patch links are provided, users should verify and upgrade to these fixed versions.

Description

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Fedify previously addressed SSRF/internal network access in GHSA-p9cg-vqcc-grcx by adding public URL validation before runtime document and media fetching. However, the IPv4 validation logic present starting in version 0.11.2 and prior to versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 appears incomplete. The `validatePublicUrl()` protection relies on `isValidPublicIPv4Address()` to reject non-public IPv4 destinations. The function blocks common private and local ranges such as `10.0.0.0/8`, `127.0.0.0/8`, `169.254.0.0/16`, `172.16.0.0/12`, and `192.168.0.0/16`, but it still treats several special-use, reserved, multicast, benchmarking, and carrier-grade NAT IPv4 ranges as valid public destinations. Because this validation is used as an SSRF defense before outbound fetches, this appears to be an incomplete mitigation or bypass class for the previous SSRF issue. Versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 contain an updated patch.

Impact

Successful exploitation allows an attacker to perform server-side request forgery (SSRF), potentially accessing internal network resources or services that should be inaccessible. This can lead to information disclosure (high confidentiality impact), limited integrity impact, and limited availability impact. The CVSS score of 8.6 reflects high severity with network attack vector, low attack complexity, no privileges required, and no user interaction needed.

Summary

Fedify previously implemented SSRF protections by validating public URLs before fetching documents and media. However, the IPv4 validation logic in versions >=0.11.2 and <1.9.12, <1.10.11, <2.0.19, <2.1.15, and <2.2.4 is incomplete. The isValidPublicIPv4Address() function blocks common private and local IP ranges but does not block several special-use, reserved, multicast, benchmarking, and carrier-grade NAT IPv4 ranges. Since validatePublicUrl() depends on this function, SSRF protections can be bypassed, allowing an attacker to make server-side requests to unintended internal or reserved IP addresses. The issue is addressed in versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 with updated patches.

CWE-918Server-Side Request Forgery (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.
Implementation · Operation
If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Operation
If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
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).
CWE-1286Improper Validation of Syntactic Correctness of Input (opens in a new tab)
Base weakness
The product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
SQL Injection (opens in a new tab)
NoSQL Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1389Incorrect Parsing of Numbers with Different Radices (opens in a new tab)
Base weakness
The product parses numeric input assuming base 10 (decimal) values, but it does not account for inputs that use a different base number (radix).
Implementation · Enforcement by Conversion
If only decimal-based values are expected in the application, conditional checks should be created in a way that prevent octal or hexadecimal strings from being checked.
Implementation · Input Validation
If various numerical bases do need to be supported, check for leading values indicating the non-decimal base you wish to support (such as 0x for hex) and convert the numeric strings to integers of the respective base. Reject any other alternative-base string that is not intentionally supported by the application.
Implementation · Input Validation
If regular expressions are used to validate IP addresses, ensure that they are bounded using ^ and $ to prevent base-prepended IP addresses from being matched.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/fedify-dev/fedify/security/advisories/GHSA-xw9q-2mv6-9fr8 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Jun 2026, 21:13 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-918, CWE-1286, CWE-1389

Technical details

References

Community reviews

Related threats