CVE-2026-59998

MEDIUM

Published Jul 8, 2026 Modified Jul 9, 2026 CWE-573

Description

sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has no value if the server is in Windows Active Directory.

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CVSS v3.1 Score

4.8

MEDIUM

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

EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.08%

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-573 CWE-573

Affected Products

Vendor	Product	Versions
openbsd	openssh	< 10.4

References

Other References

https://marc.info/?l=openssh-unix-dev&m=178333966933090&w=2 https://www.openssh.org/releasenotes.html#10.4p1 https://www.openwall.com/lists/oss-security/2026/07/06/5

Frequently Asked Questions

What is CVE-2026-59998? +

sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has no value if the server is in Windows Active Directory. It has a CVSS v3.1 base score of 4.8 (MEDIUM).

How severe is CVE-2026-59998? +

CVE-2026-59998 has a CVSS v3.1 score of 4.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0018, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-59998? +

CVE-2026-59998 affects products from openbsd, specifically: openssh. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-59998? +

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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