universal-modder: Missing Origin Validation in WebSockets
CVE-2026-125358 is a high-severity missing origin validation in websockets vulnerability in universal-modder from Rehan-remade, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version e88f6876745427321eb755ebc98276063a962d8a as the first without the flaw, so updating universal-modder to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.18% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update universal-modder to e88f6876745427321eb755ebc98276063a962d8a or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Rehan-remade | universal-modder | before e88f6876745427321eb755ebc98276063a962d8a | e88f6876745427321eb755ebc98276063a962d8a |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.2 | High | CNA (vulncheck.com) |
| CVSS 3.1 | 8.1 | High | CNA (vulncheck.com) |
Official description
Universal-modder before commit e88f6876745427321eb755ebc98276063a962d8a contains a missing WebSocket Origin validation vulnerability in the HostLink class of its passthrough example mods that allows remote attackers to execute Minecraft commands. Any web page open in the player's browser can connect cross-site to the unauthenticated loopback WebSocket and send cmd messages that WorldBridge.command() runs with operator authority.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Origin Validation in WebSockets
The product uses a WebSocket, but it does not properly verify that the source of data or communication is valid.
How developers prevent this class of flaw
- Enable CORS-like access restrictions by verifying the 'Origin' header during the WebSocket handshake.
- Use a randomized CSRF token to verify requests.
- Use TLS to securely communicate using 'wss' (WebSocket Secure) instead of 'ws'.
More Missing Origin Validation in WebSockets vulnerabilities (CWE-1385)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Missing Origin Validation in WebSockets vulnerabilities
- 8.7 High severity
- 8.1 High severity
- 9.3 Critical severity
- 7.5 High severity
- 8.1 High severity
- 9.3 Critical severity
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