CVE-2026-88231: Windows iSCSI Information Disclosure Vulnerability
CVE-2026-88231 is an information disclosure vulnerability in Windows iSCSI, rated Important by Microsoft, with a CVSS 3.1 base score of 5.7 (Medium). An attacker can exploit it remotely over the network, with low privileges and only if a user takes an action. Microsoft has not reported exploitation in the wild and rates exploitation as less likely. Microsoft released the fix on 10 November 2026 in the November 2026 Patch Tuesday, delivered through 10 security updates (KB5131291, KB5131085, KB5131096, KB5131090 and more). It affects 28 products in 2 product families (ESU, Windows).
Key facts
- CVE ID
- CVE-2026-88231
- Severity
- Medium CVSS 5.7
- Microsoft severity
- Important
- Impact
- Information Disclosure
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- Less Likely
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- ESU, Windows
CVSS score and vector
Microsoft scores CVE-2026-88231 at 5.7 (temporal 5) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | None |
| Availability impact | None |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Out-of-bounds read in Windows iSCSI allows an authorized attacker to disclose information over a network.
Frequently asked questions (Microsoft)
What type of information could be disclosed by this vulnerability?
An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.
Affected products (28)
ESU
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1607 for 32-bit Systems | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows 10 Version 1607 for x64-based Systems | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows Server 2016 | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows Server 2016 (Server Core installation) | KB5131291 | Security Update | 10.0.14393.9688 | Yes |
| Windows 10 Version 22H2 for 32-bit Systems | ||||
| Windows 10 Version 22H2 for ARM64-based Systems | ||||
| Windows 10 Version 22H2 for x64-based Systems |
Windows
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1809 for 32-bit Systems | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows 10 Version 1809 for x64-based Systems | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows Server 2019 | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows Server 2019 (Server Core installation) | KB5131085 | Security Update | 10.0.17763.9487 | Yes |
| Windows 10 Version 21H2 for 32-bit Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows 10 Version 21H2 for ARM64-based Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows 10 Version 21H2 for x64-based Systems | KB5131096 | Security Update | 10.0.19044.7846 | Yes |
| Windows Server 2022 | KB5131090 | Security Update | 10.0.20348.5870 | Yes |
| Windows Server 2022 (Server Core installation) | KB5131090 | Security Update | 10.0.20348.5870 | Yes |
| Windows 11 Version 23H2 for ARM64-based Systems | KB5131087 | Security Update | 10.0.22631.7711 | Yes |
| Windows 11 Version 23H2 for x64-based Systems | KB5131087 | Security Update | 10.0.22631.7711 | Yes |
| Windows 11 Version 24H2 for ARM64-based Systems | KB5132061 KB5132043 | Security Update Security Update | 10.0.26100.9974 10.0.26100.9911 | Yes No |
| Windows 11 Version 24H2 for x64-based Systems | KB5132061 KB5132043 | Security Update Security Update | 10.0.26100.9974 10.0.26100.9911 | Yes No |
| Windows 11 Version 25H2 for ARM64-based Systems | KB5132043 | Security Update | 10.0.26200.9911 | No |
| Windows 11 Version 25H2 for x64-based Systems | KB5132043 | Security Update | 10.0.26200.9911 | No |
| Windows 11 Version 26H2 for ARM64-based Systems | KB5132043 | Security Update | 10.0.26300.9911 | No |
| Windows 11 Version 26H2 for x64-based Systems | KB5132043 | Security Update | 10.0.26300.9911 | No |
| Windows Server 2025 | KB5131080 KB5131077 | Security Update Security Update | 10.0.26100.33822 10.0.26100.33730 | Yes No |
| Windows Server 2025 (Server Core installation) | KB5131080 KB5131077 | Security Update Security Update | 10.0.26100.33822 10.0.26100.33730 | Yes No |
| Windows 11 Version 26H1 for ARM64-based Systems | KB5132059 | Security Update | 10.0.28000.3501 | Yes |
| Windows 11 version 26H1 for x64-based Systems | KB5132059 | Security Update | 10.0.28000.3501 | Yes |
Security updates (10)
Acknowledgments
- yhw
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |