CVE-2026-21530

MEDIUM

Published May 12, 2026 Modified May 14, 2026 CWE-415

Description

Double free in Windows Rich Text Edit allows an authorized attacker to elevate privileges locally.

CVSS v3.1 Score

6.7

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0005

Probability of exploitation

0.17%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-415 CWE-415

Affected Products

Vendor	Product	Versions
microsoft	windows_10_1607	< 10.0.14393.9140
microsoft	windows_10_1607	< 10.0.14393.9140
microsoft	windows_10_1809	< 10.0.17763.8755
microsoft	windows_10_1809	< 10.0.17763.8755
microsoft	windows_10_21h2	< 10.0.19044.7291
microsoft	windows_10_21h2	< 10.0.19044.7291
microsoft	windows_10_21h2	< 10.0.19044.7291
microsoft	windows_10_22h2	< 10.0.19045.7291
microsoft	windows_10_22h2	< 10.0.19045.7291
microsoft	windows_10_22h2	< 10.0.19045.7291
microsoft	windows_11_23h2	< 10.0.22631.7079
microsoft	windows_11_23h2	< 10.0.22631.7079
microsoft	windows_11_24h2	< 10.0.26100.8390
microsoft	windows_11_24h2	< 10.0.26100.8390
microsoft	windows_11_25h2	< 10.0.26200.8457
microsoft	windows_11_25h2	< 10.0.26200.8457
microsoft	windows_11_26h1	< 10.0.28000.2113
microsoft	windows_11_26h1	< 10.0.28000.2113
microsoft	windows_server_2012	All
microsoft	windows_server_2012	All
microsoft	windows_server_2016	< 10.0.14393.9140
microsoft	windows_server_2019	< 10.0.17763.8755
microsoft	windows_server_2022	< 10.0.20348.5139
microsoft	windows_server_2022_23h2	< 10.0.25398.2330
microsoft	windows_server_2025	< 10.0.26100.32860

References

Advisories & Patches

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21530

Frequently Asked Questions

What is CVE-2026-21530? +

Double free in Windows Rich Text Edit allows an authorized attacker to elevate privileges locally. It has a CVSS v3.1 base score of 6.7 (MEDIUM).

How severe is CVE-2026-21530? +

CVE-2026-21530 has a CVSS v3.1 score of 6.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0005, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-21530? +

CVE-2026-21530 affects products from microsoft, specifically: windows_10_1607, windows_10_1809, windows_10_21h2, windows_10_22h2, windows_11_23h2, windows_11_24h2, windows_11_25h2, windows_11_26h1, windows_server_2012, windows_server_2016, windows_server_2019, windows_server_2022, windows_server_2022_23h2, windows_server_2025. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-21530? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-2027

A double free vulnerability has been identified in the ASUS System Analysis service. This vulnerability can be triggered by sending …

CVE-2025-8058

The regcomp function in the GNU C library version from 2.4 to 2.41 is subject to a double free if …

CVE-2024-22097 9.8

A double-free vulnerability exists in the BrainVision Header Parsing functionality of The Biosig Project libbiosig Master Branch (ab0ee111) and 2.5.0. …

CVE-2024-23809 9.8

A double-free vulnerability exists in the BrainVision ASCII Header Parsing functionality of The Biosig Project libbiosig 2.5.0 and Master Branch …

CVE-2024-27099 9.8

The uAMQP is a C library for AMQP 1.0 communication to Azure Cloud Services. When processing an incorrect `AMQP_VALUE` failed …

CVE-2024-10934 9.8

In OpenBSD 7.5 before errata 008 and OpenBSD 7.4 before errata 021, avoid possible mbuf double free in NFS client …