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Fencer Vulns
critical 9.8

CVE-2026-64620 json

FreeRDP before 3.28.0 Heap Buffer Overflow via crypto_rsa_common

published 2026-07-20 3 mo ago modified 2026-07-28 3 mo ago also EUVD-2026-45935

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

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.

Patch / fix

  • FreeRDP FreeRDP 3.28.0
  • freerdp3 Debian 14 3.28.0+dfsg-1

debian advisories DEBIAN-CVE-2026-64620

  • freerdp3 Ubuntu 24.04 LTS 3.30.0+dfsg-0ubuntu0.24.04.1
  • freerdp3 Ubuntu 26.04 LTS 3.30.0+dfsg-0ubuntu0.26.04.1

ubuntu advisories UBUNTU-CVE-2026-64620

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • freerdp RHEL 10.2 2:3.10.3-12.el10_2.8
  • libwinpr RHEL 10.2 2:3.10.3-12.el10_2.8
  • freerdp-libs RHEL 10.2 2:3.10.3-12.el10_2.8
  • freerdp-server RHEL 10.2 2:3.10.3-12.el10_2.8
  • freerdp enterprise linux eus 10.0 2:3.10.3-3.el10_0.11
  • libwinpr enterprise linux eus 10.0 2:3.10.3-3.el10_0.11
  • freerdp-libs enterprise linux eus 10.0 2:3.10.3-3.el10_0.11
  • freerdp-server enterprise linux eus 10.0 2:3.10.3-3.el10_0.11

red hat advisories RHSA-2026:58711RHSA-2026:54486

  • freerdp AlmaLinux 10 2:3.10.3-12.el10_2.8
  • libwinpr AlmaLinux 10 2:3.10.3-12.el10_2.8
  • freerdp-libs AlmaLinux 10 2:3.10.3-12.el10_2.8
  • freerdp-server AlmaLinux 10 2:3.10.3-12.el10_2.8

almalinux advisories ALSA-2026:54486

  • freerdp Rocky Linux 10 2:3.10.3-12.el10_2.8

rocky linux advisories RLSA-2026:54486

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64620 updated cvss 8.1

FreeRDP: FreeRDP: Remote code execution or denial of service via heap-based buffer overflow

  • Red Hat Enterprise Linux 6 freerdp, freerdp-libs, freerdp-plugins
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 10) freerdp 3.10.3-12.el10_2.8, libwinpr 3.10.3-12.el10_2.8, freerdp-libs 3.10.3-12.el10_2.8
    fixed: vendor fix RHSA-2026:54486
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) freerdp 3.10.3-3.el10_0.11, libwinpr 3.10.3-3.el10_0.11, freerdp-libs 3.10.3-3.el10_0.11
    fixed: vendor fix RHSA-2026:58711
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-server 3.10.3-12.el10_2.8
    fixed: vendor fix RHSA-2026:54486
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) freerdp-server 3.10.3-3.el10_0.11
    fixed: vendor fix RHSA-2026:58711
  • Red Hat Enterprise Linux 7 freerdp, libwinpr, freerdp-libs, freerdp-plugins
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 8 freerdp, libwinpr, freerdp-libs
    not affected: component not present
  • Red Hat Enterprise Linux 9 freerdp, libwinpr, freerdp-libs
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
3 mo ago

Exploit prediction

0.91% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pjqx-v446-x7fc referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Affected products

  • FreeRDP FreeRDP

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.