CVE-2023-34048
CVE-2023-34048 is a security flaw in VMware vCenter Server, VMware’s software for running virtual machines in data centres. Attackers can run their own code on VMware vCenter Server. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 22 Jan 2024.[1]
VMware vCenter Server 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. Fixed in version 8.0U2, 7.0U3o and KB88287.
Description
CISA calls it an out-of-bounds write in VMware vCenter Server. In its words: “VMware vCenter Server contains an out-of-bounds write vulnerability in the implementation of the DCERPC protocol that allows an attacker to conduct remote code execution.”[1]
The CVE record adds: “vCenter Server contains an out-of-bounds write vulnerability in the implementation of the DCERPC protocol. A malicious actor with network access to vCenter Server may trigger an out-of-bounds write potentially leading to remote code execution.”[2]
The underlying weakness is out-of-bounds write (CWE-787), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| VMware vCenter Server | 8.0U2 |
| VMware vCenter Server | 7.0U3o |
| vcenter_server | 7.0U3o |
| vcenter_server | 8.0U2 |
| cloud_foundation | KB88287 |
Most families won’t have VMware vCenter Server; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 22 Jan 2024, 89 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 12 Feb 2024 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 99%. That’s in the top 1% 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 mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.VMware vCenter Server 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 (fixed in version 8.0U2, 7.0U3o and KB88287), or not in use. CISA gave US government agencies until 12 Feb 2024 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 9.8.[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 99%.[4] |
See also
Other VMware vCenter Server flaws
- CVE-2024-38813: privilege escalation ·
- CVE-2024-38812: heap-based buffer overflow ·
- CVE-2022-22948: incorrect default file permissions ·
- CVE-2021-22017: improper access control ·
- CVE-2021-22005: file upload ·
- CVE-2021-21985: improper input validation ·
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-2024-37085, VMware ESXi: authentication bypass ·
- CVE-2023-20867, VMware Tools: authentication bypass ·
Other out-of-bounds write flaws
- CVE-2026-86950, Apple devices: out-of-bounds write ·
- CVE-2026-53266, Linux Kernel: out-of-bounds write ·
- CVE-2026-87491, Chrome and other Chromium browsers: out of bounds write ·
- CVE-2026-53362, Linux Kernel: unspecified ·
- CVE-2022-0995, Linux Kernel: out-of-bounds write ·
Every VMware flaw on CISA’s list · Everything added in January 2024
References
- ^ Cybersecurity and Infrastructure Security Agency. “VMware vCenter Server Out-of-Bounds Write Vulnerability”. Known Exploited Vulnerabilities Catalog, added 22 Jan 2024.
- ^ National Institute of Standards and Technology. “CVE-2023-34048 Detail”. National Vulnerability Database, published 25 Oct 2023.
- ^ VMware. Advisories and fixes: vmware.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.992, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2023-34048”. 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.