# CVE-2026-91964 — FreeRDP

> As of 2026-11-14, CVE-2026-91964 is a HIGH-severity vulnerability in FreeRDP, CVSS v3.1 8.8, EPSS 0.6% (49.4th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-91964, most recently “FreeRDP client-side RCE chain (CVE-2026-91964 heap overflow + CVE-2026-91963 USB redirection heap disclosure) found via AI-agent vulnerability research workflow”.

**Last updated:** 2026-11-14

## What is CVE-2026-91964?

FreeRDP versions before 3.31.0 contain a heap-based buffer overflow in nego_send_negotiation_request when processing Server Redirection PDU messages with attacker-controlled LoadBalanceInfo fields. A malicious RDP server can trigger the overflow by sending an arbitrary-length field that gets written to a fixed 512-byte buffer without validation, causing client crashes or potential code execution when chained with memory disclosure.

The record classifies CVE-2026-91964 under weakness class [CWE-122](https://intel.threadlinqs.com/cwe/CWE-122). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 61 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.8 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **CVSS v4.0 base score:** 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **EPSS (FIRST):** 0.6% probability of exploitation in the next 30 days, higher than 49.4% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 8.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-15

## Is CVE-2026-91964 being exploited?

Weaponised exploit code for CVE-2026-91964 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

- [trickest/cve](https://github.com/trickest/cve/blob/main/2026/CVE-2026-91964.md) (trickest)

## Affected products and versions

- **FreeRDP**: FreeRDP

## How to fix CVE-2026-91964

Vendor advisory: [https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-2vf2-grvj-6g8x](https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-2vf2-grvj-6g8x). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2026-91964

1 tracked threat in the Threadlinqs corpus references CVE-2026-91964, either in the campaign’s CVE list or as an indicator on the campaign record.

- [FreeRDP client-side RCE chain (CVE-2026-91964 heap overflow + CVE-2026-91963 USB redirection heap disclosure) found via AI-agent vulnerability research workflow](https://intel.threadlinqs.com/threat/TL-2026-6098) — HIGH · 2026-11-14

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories.

**Vendor advisory and patch**

- [github.com — vendor advisory](https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-2vf2-grvj-6g8x)

**Third-party advisory**

- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/freerdp-2.0.0-through-3.30.0-heap-buffer-overflow-via-routingtoken)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-91964
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