CVE-2026-91958: Out-of-bounds Read (CVSS 6.6)

Description

FreeRDP versions before 3.31.0 fail to validate MonitorIds array values when parsing RDP connection files, allowing unbounded array indexing in xf_detect_monitors. Attackers can craft a malicious RDP file with an out-of-range selectedmonitors value to trigger out-of-bounds heap read and write operations when opened in xfreerdp.

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CVSS v3.1 Score

6.6

MEDIUM

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

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.10%

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-125 Out-of-bounds Read

References

Other References

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-23pf-q83q-x45r https://www.vulncheck.com/advisories/freerdp-3.11.0-through-3.30.0-heap-buffer-overflow-via-monitor-index https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-23pf-q83q-x45r

Frequently Asked Questions

What is CVE-2026-91958? +

FreeRDP versions before 3.31.0 fail to validate MonitorIds array values when parsing RDP connection files, allowing unbounded array indexing in xf_detect_monitors. Attackers can craft a malicious RDP file with an out-of-range selectedmonitors value to trigger out-of-bounds heap read and write operations when opened in xfreerdp. It has a CVSS v3.1 base score of 6.6 (MEDIUM).

How severe is CVE-2026-91958? +

CVE-2026-91958 has a CVSS v3.1 score of 6.6 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-91958? +

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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