MySQL2: Auth Plugin Downgrade to mysql_clear_password Leaks Plaintext Credentials
Summary
A rogue MySQL server (or MITM) can force mysql2 to send credentials in plaintext by requesting an auth switch to mysql_clear_password. The driver complies without verifying that TLS is active.
Details
mysql_clear_password is registered as a default standard plugin in lib/commands/auth_switch.js (line 21). When a server sends an AuthSwitchRequest (0xFE) requesting mysql_clear_password, the driver executes it without checking for TLS. The plugin (lib/auth_plugins/mysql_clear_password.js) returns Buffer.from(password + '\0').
Note: caching_sha2_password plugin DOES check for SSL before sending cleartext (line 77). But mysql_clear_password has no such guard.
Attack Scenario
- Attacker operates rogue MySQL server or performs MITM
- Server advertises
caching_sha2_passwordin handshake - Client sends hashed auth response
- Server replies with AuthSwitchRequest to
mysql_clear_password - Client sends password in plaintext
- Attacker captures plaintext password
PoC
Rogue MySQL server (Node.js, ~80 lines) that captures plaintext passwords from mysql2 clients. Tested against mysql2 3.20.0. Full PoC available on request.
Suggested Fix
Remove mysql_clear_password from standardAuthPlugins, or add a guard requiring TLS/unix socket before allowing cleartext auth.
Impact
- mysql2: 9M weekly downloads
- Any application connecting without TLS is vulnerable to credential theft
- Cloud environments with untrusted network paths are especially at risk
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | mysql2 | < 3.22.0 | 3.22.0 |
References
- https://github.com/sidorares/node-mysql2/security/advisories/GHSA-3f6p-5ww8-9rcr
- https://github.com/sidorares/node-mysql2/issues/1617
- https://github.com/sidorares/node-mysql2/pull/4236
- https://github.com/sidorares/node-mysql2/commit/884bec56288d827939d0dd3f1f4ae476fbc8dbeb
- https://github.com/sidorares/node-mysql2
- https://github.com/sidorares/node-mysql2/releases/tag/v3.22.0
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-522- Platform
- npm
- Package
mysql2- Disclosed
- 01.09.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-3f6p-5ww8-9rcr - CC BY 4.0
Vulnerability history: mysql2
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 7
- First → latest
- 04.2024 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 2
- Medium 3
Disclosures per year
- 2024: 5
- 2025: 0
- 2026: 2
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MySQL2: Auth Plugin Downgrade to mysql_clear_password Leaks Plaintext Credentials this entry
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