CVE-2023-20867
CVE-2023-20867 is a security flaw in VMware Tools, VMware’s software for running virtual machines in data centres. Attackers can get into VMware Tools without a valid password. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 23 Jun 2023.[1]
VMware Tools is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. VMware has published a fix or advice.
Description
CISA calls it an authentication bypass in VMware Tools. In its words: “VMware Tools contains an authentication bypass vulnerability in the vgauth module. A fully compromised ESXi host can force VMware Tools to fail to authenticate host-to-guest operations, impacting the confidentiality and integrity of the guest virtual machine. An attacker must have root access over ESXi to exploit this vulnerability.”[1]
The underlying weakness is improper authentication (CWE-287), in MITRE’s list of common software weaknesses.[2]
It scores 3.9 out of 10 on the Common Vulnerability Scoring System, which rates it low, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; VMware’s advisory has them[3]. CISA names the product as VMware Tools.
Most families won’t have VMware Tools; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 23 Jun 2023, 10 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 14 Jul 2023 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 14%. That’s in the top 4% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
VMware has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.VMware Tools is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 14 Jul 2023 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 3.9.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 14%.[4] |
See also
Other VMware flaws
- CVE-2025-22226, VMware ESXi, Workstation, and Fusion: information disclosure ·
- CVE-2025-22225, VMware ESXi: arbitrary write ·
- CVE-2025-22224, VMware ESXi and Workstation: TOCTOU race condition ·
- CVE-2024-38813, VMware vCenter Server: privilege escalation ·
- CVE-2024-38812, VMware vCenter Server: heap-based buffer overflow ·
Other improper authentication flaws
- CVE-2026-105133, AhsayCBS: improper authentication ·
- CVE-2026-42018, JFrog Artifactory: improper authentication ·
- CVE-2026-82329, JFrog Artifactory: improper authentication ·
- CVE-2026-59822, BerriAI LiteLLM: improper authentication ·
- CVE-2023-49105, ownCloud: improper authentication ·
Added the same day
- CVE-2023-32439, Apple devices: webKit type confusion ·
- CVE-2023-32435, Apple devices: webKit memory corruption ·
- CVE-2023-32434, Apple devices: integer overflow ·
- CVE-2023-27992, Zyxel Multiple Network-Attached Storage (NAS) Devices: multiple NAS devices command injection ·
Every VMware flaw on CISA’s list · Everything added in June 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “VMware Tools Authentication Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 23 Jun 2023.
- ^ National Institute of Standards and Technology. “CVE-2023-20867 Detail”. National Vulnerability Database, published 13 Jun 2023.
- ^ VMware. Advisories and fixes: vmware.com, lists.fedoraproject.org, lists.fedoraproject.org, lists.fedoraproject.org.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.136, percentile 96.5, 31 Oct 2026.
- CVE Program. “CVE-2023-20867”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.