CVE-2026-34339

MEDIUM

Published May 12, 2026 Modified May 14, 2026 CWE-476

Description

Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an authorized attacker to deny service locally.

CVSS v3.1 Score

5.5

MEDIUM

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

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.13%

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-476 CWE-476

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	< 10.0.26200.8390
microsoft	windows_11_25h2	< 10.0.26200.8390
microsoft	windows_11_26h1	< 10.0.28000.2113
microsoft	windows_11_26h1	< 10.0.28000.2113
microsoft	windows_server_2016	< 10.0.14393.9140
microsoft	windows_server_2019	< 10.0.17763.8755
microsoft	windows_server_2022	< 10.0.20348.5074
microsoft	windows_server_2022_23h2	< 10.0.25398.2330
microsoft	windows_server_2025	< 10.0.26100.32772

References

Advisories & Patches

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34339

Frequently Asked Questions

What is CVE-2026-34339? +

Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an authorized attacker to deny service locally. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-34339? +

CVE-2026-34339 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-34339? +

CVE-2026-34339 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_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-2026-34339? +

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.

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