Universal-modder before e88f687 Cross-Site WebSocket Command Execution via HostLink
Universal-modder builds before commit e88f687 are exposed when the Minecraft passthrough mod with HostLink is loaded. The fix is in commit e88f687.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fix or patch referenced
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. The Minecraft passthrough mod with HostLink is loaded and its WebSocket server is listening on 127.0.0.1:25599. A web page is open in the player's browser while the mod is loaded.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 19/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Universal-modder, a Minecraft modding tool, before commit e88f687 has a missing WebSocket Origin check in the HostLink class of its passthrough example mods. A remote attacker can lure a player to a web page that connects to the unauthenticated loopback WebSocket and run Minecraft commands with operator authority, which can change the game state.
Read the original 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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.2/10CVSS 7.2
- No patch0/5No signal
What would change the score
- Would score about 69 if added to CISA KEV
- Would score about 64 if CISA's SSVC rates exploitation active
What to do
Check whether your setup matches what the bug needs.
The Minecraft passthrough mod with HostLink is loaded and its WebSocket server is listening on 127.0.0.1:25599. A web page is open in the player's browser while the mod is loaded.Apply the patch listed under Evidence.
Workaround: Close Minecraft while browsing the web.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- rehan-remade universal-modder
Version range not reported
Evidence 4
- Advisory
- Patch
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-125358
Is CVE-2026-125358 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
HostLink opens a local WebSocket server on 127.0.0.1:25599 that did not reject connections from web pages. A malicious web page that is open while the mod is loaded can send Minecraft commands that run with operator authority in the player's world, including LAN worlds the player hosts.Source: github.com
Am I affected, and how do I check?
Builds of Universal-modder before commit e88f687 are affected when the Minecraft passthrough mod with HostLink is loaded and its WebSocket server is listening on 127.0.0.1:25599. To check, look for HostLink in the loaded mods and confirm the build's commit hash against e88f687.Source: github.com
How do I fix CVE-2026-125358?
Update Universal-modder to a build that includes commit e88f687 or later. The fix makes HostLink refuse any WebSocket handshake that carries an Origin header.Source: github.com