CVE-2019-6706: Lua 5.3.5 has a use-after-free in lua_upvaluejoin in lapi.c. For example a crash outcome might be achieved by an attacker who is able to trigger a debug.upvaluejoin call in which the arguments have certain relationships.
Overview
- Severity
- High (CVSS 7.5)
- CVSS Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Exploit Status
- Not Exploited
- Patch Tuesday
- 2026-Aug
- Released
- 2020-09-25
- Last Updated
- 2026-08-07
- EPSS Score
- 17.22% (percentile: 96.8%)
FAQ
Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability?
One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.
Affected Products (3)
Mariner
- cm1 lua 5.3.5-8 on CBL Mariner 1.0
- cbl2 lua 5.3.5-11 on CBL Mariner 2.0
- azl3 lua 5.4.6-1 on Azure Linux 3.0
Revision History
- 2020-09-25: Information published.
- 2021-12-16: Added lua to CBL-Mariner 2.0
- 2026-08-07: Information published.