MySQL2: Auth Plugin Downgrade to mysql_clear_password Leaks Plaintext Credentials

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.2 · 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 · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary A rogue MySQL server (or MITM) can force mysql2 to send credentials in plaintext by requesting an auth switch to mysqlclearpassword. The driver complies without verifying that TLS is active. Details mysqlclearpassword is registered as a default standard plugin in lib/commands/authswitch.js (line 21). When a server sends an AuthSwitchRequest (0xFE) requesting mysqlclearpassword, the driver executes it without checking for TLS. The plugin (lib/authplugins/mysqlclearpassword.js) returns Buffer.from(password + '\0'). Note: cachingsha2password plugin DOES check for SSL before sending cleartext (line 77). But mysqlclearpassword has no such guard. Attack Scenario 1. Attacker operates rogue MySQL server or performs MITM 2. Server advertises cachingsha2password in handshake 3. Client sends hashed auth response 4. Server replies with AuthSwitchRequest to mysqlclearpassword 5. Client sends password in plaintext 6. Attacker captures plaintext password PoC Rogue MySQL server (Node.js, ~80…

Published by the source

1 Sep 2026, 16:40 UTC

Last modified by the source

1 Sep 2026, 16:40 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3f6p-5ww8-9rcr

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# Patch Next advisory brief: GHSA-3f6p-5ww8-9rcr

Advisory: MySQL2: Auth Plugin Downgrade to mysql_clear_password Leaks Plaintext Credentials
IDs: GHSA-3f6p-5ww8-9rcr
Record: https://patchnext.com/advisories/ghsa-3f6p-5ww8-9rcr (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mysql2 3.22.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm mysql2: affected < 3.22.0; fixed in 3.22.0

## Suggested inspection (read-only)
- `npm ls mysql2 --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mysql2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3f6p-5ww8-9rcr (GitHub-reviewed advisory GHSA-3f6p-5ww8-9rcr lists affected ranges: npm mysql2 >=0 <3.22.0)

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