CVE-2026-91960: Integer Overflow (CVSS 6.5)

Description

FreeRDP versions before 3.31.0 contain an integer overflow in WinPR's Stream_EnsureRemainingCapacity function that allows remote attackers to cause denial of service. A malicious RD Gateway peer can send a WebSocket Ping frame with a crafted 64-bit extended payload length to trigger integer wraparound, resulting in a double free that crashes the FreeRDP client during connection.

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CVSS v3.1 Score

6.5

MEDIUM

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

EPSS — Exploit Prediction

0.0044

Probability of exploitation

0.38%

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-190 Integer Overflow

References

Other References

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vccg-35r5-8jrf https://www.vulncheck.com/advisories/freerdp-before-3.31.0-integer-overflow-double-free https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vccg-35r5-8jrf

Frequently Asked Questions

What is CVE-2026-91960? +

FreeRDP versions before 3.31.0 contain an integer overflow in WinPR's Stream_EnsureRemainingCapacity function that allows remote attackers to cause denial of service. A malicious RD Gateway peer can send a WebSocket Ping frame with a crafted 64-bit extended payload length to trigger integer wraparound, resulting in a double free that crashes the FreeRDP client during connection. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-91960? +

CVE-2026-91960 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0044, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-91960? +

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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