# CVE-2026-64620: freerdp3-shadow-x11: FreeRDP before 3.28.0 (affected <=3.27.1) contains a heap-based buffer overflow in crypto_rsa_common() (libfreerdp...

CVE-2026-64620 is fixed in 34 products on 1 platform, first by DEBIAN-CVE-2026-64620, released July 21, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-64620
- Priority: High
- CVSS: 9.1 (Medium)
- EPSS: 0.0091
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 20, 2026

## Description

FreeRDP before 3.28.0 (affected <=3.27.1) contains a heap-based buffer overflow in crypto_rsa_common() (libfreerdp/crypto/crypto.c). The function writes the modular-exponentiation result into the caller's output buffer via BN_bn2bin() and only afterward checks output_length > out_length, so out-of-bounds bytes are written before the bounds check. On the server side, when a client selects RDP Standard Security, the encrypted client random is decrypted into a fixed 32-byte buffer. Because the server publishes its RSA public key, an unauthenticated attacker can forge a ciphertext whose decrypted value is up to the full modulus length (e.g. 256 bytes for RSA-2048), overflowing the 32-byte heap buffer by up to ~224 attacker-controlled bytes pre-authentication, resulting in denial of service.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | freerdp RHEL 10 | 3.10.3-3.el10_0.11 | [RHSA-2026:58711](https://patchblox.com/security/data/fix/linux/rhsa-2026-58711.md) | Aug 14, 2026 |
| Linux | freerdp almalinux 10 | 2:3.10.3-12.el10_2.8 | [ALSA-2026:54486](https://patchblox.com/security/data/fix/linux/alsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp ol 10 | 2:3.10.3-12.el10_2.8 | [ELSA-2026-54486](https://patchblox.com/security/data/fix/linux/elsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp rocky 10 | 2:3.10.3-12.el10_2.8 | [RLSA-2026:54486](https://patchblox.com/security/data/fix/linux/rlsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp-debuginfo amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp-debugsource amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp-devel almalinux 10 | 2:3.10.3-12.el10_2.8 | [ALSA-2026:54486](https://patchblox.com/security/data/fix/linux/alsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp-devel amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp-devel ol 10 | 2:3.10.3-12.el10_2.8 | [ELSA-2026-54486](https://patchblox.com/security/data/fix/linux/elsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp-libs almalinux 10 | 2:3.10.3-12.el10_2.8 | [ALSA-2026:54486](https://patchblox.com/security/data/fix/linux/alsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp-libs amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp-libs ol 10 | 2:3.10.3-12.el10_2.8 | [ELSA-2026-54486](https://patchblox.com/security/data/fix/linux/elsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp-libs-debuginfo amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp-proxy Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp-proxy 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp-proxy-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp-proxy-modules Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp-proxy-modules 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp-proxy-modules-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp-sdl Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp-sdl 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp-sdl-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp-server almalinux 10 | 2:3.10.3-12.el10_2.8 | [ALSA-2026:54486](https://patchblox.com/security/data/fix/linux/alsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp-server amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp-server ol 10 | 2:3.10.3-12.el10_2.8 | [ELSA-2026-54486](https://patchblox.com/security/data/fix/linux/elsa-2026-54486.md) | Aug 13, 2026 |
| Linux | freerdp-server-debuginfo amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | freerdp-shadow-x11 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp-shadow-x11 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp-shadow-x11-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp-wayland Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp-wayland 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp-wayland-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp-x11 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp-x11 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp-x11-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp3 Debian 14 | 3.28.0+dfsg-1 | [DEBIAN-CVE-2026-64620](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64620.md) | Jul 21, 2026 |
| Linux | freerdp3-proxy Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp3-proxy 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp3-proxy-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp3-proxy-modules Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp3-proxy-modules 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp3-proxy-modules-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp3-sdl Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp3-sdl 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp3-sdl-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp3-shadow-x11 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [freerdp3-shadow-x11 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-freerdp3-shadow-x11-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | freerdp3-shadow-x11 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp3-shadow-x11 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp3-shadow-x11-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp3-wayland Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [freerdp3-wayland 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-freerdp3-wayland-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | freerdp3-wayland Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp3-wayland 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp3-wayland-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | freerdp3-x11 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [freerdp3-x11 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-freerdp3-x11-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | freerdp3-x11 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [freerdp3-x11 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-freerdp3-x11-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libfreerdp-client3-3 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [libfreerdp-client3-3 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libfreerdp-client3-3-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | libfreerdp-client3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libfreerdp-client3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libfreerdp-client3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libfreerdp-server-proxy3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libfreerdp-server-proxy3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libfreerdp-server-proxy3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libfreerdp-server3-3 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [libfreerdp-server3-3 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libfreerdp-server3-3-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | libfreerdp-server3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libfreerdp-server3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libfreerdp-server3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libfreerdp-shadow-subsystem3-3 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [libfreerdp-shadow-subsystem3-3 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libfreerdp-shadow-subsystem3-3-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | libfreerdp-shadow-subsystem3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libfreerdp-shadow-subsystem3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libfreerdp-shadow-subsystem3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libfreerdp-shadow3-3 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [libfreerdp-shadow3-3 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libfreerdp-shadow3-3-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | libfreerdp-shadow3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libfreerdp-shadow3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libfreerdp-shadow3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libfreerdp3-3 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [libfreerdp3-3 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libfreerdp3-3-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | libfreerdp3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libfreerdp3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libfreerdp3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libwinpr almalinux 10 | 2:3.10.3-12.el10_2.8 | [ALSA-2026:54486](https://patchblox.com/security/data/fix/linux/alsa-2026-54486.md) | Aug 13, 2026 |
| Linux | libwinpr amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | libwinpr ol 10 | 2:3.10.3-12.el10_2.8 | [ELSA-2026-54486](https://patchblox.com/security/data/fix/linux/elsa-2026-54486.md) | Aug 13, 2026 |
| Linux | libwinpr-debuginfo amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | libwinpr-devel almalinux 10 | 2:3.10.3-12.el10_2.8 | [ALSA-2026:54486](https://patchblox.com/security/data/fix/linux/alsa-2026-54486.md) | Aug 13, 2026 |
| Linux | libwinpr-devel amzn 2023 | 2:3.6.3-1.amzn2023.0.14 | [ALAS2023-2026-2053](https://patchblox.com/security/data/fix/linux/alas2023-2026-2053.md) | Aug 17, 2026 |
| Linux | libwinpr-devel ol 10 | 2:3.10.3-12.el10_2.8 | [ELSA-2026-54486](https://patchblox.com/security/data/fix/linux/elsa-2026-54486.md) | Aug 13, 2026 |
| Linux | libwinpr-tools3-3 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [libwinpr-tools3-3 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libwinpr-tools3-3-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | libwinpr-tools3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libwinpr-tools3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libwinpr-tools3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | libwinpr3-3 Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [libwinpr3-3 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libwinpr3-3-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | libwinpr3-3 Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [libwinpr3-3 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libwinpr3-3-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | winpr-utils Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [winpr-utils 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-winpr-utils-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |
| Linux | winpr3-utils Ubuntu 24.04.5 LTS (noble) | 3.30.0+dfsg-0ubuntu0.24.04.1 | [winpr3-utils 3.30.0+dfsg-0ubuntu0.24.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-winpr3-utils-3.30.0-dfsg-0ubuntu0.24.04.1.md) | Jul 23, 2026 |
| Linux | winpr3-utils Ubuntu 26.04.1 LTS (resolute) | 3.30.0+dfsg-0ubuntu0.26.04.1 | [winpr3-utils 3.30.0+dfsg-0ubuntu0.26.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-winpr3-utils-3.30.0-dfsg-0ubuntu0.26.04.1.md) | Nov 7, 2026 |

---

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