CVE-2026-64620

NameCVE-2026-64620
DescriptionFreeRDP 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
freerdp2 (PTS)bullseye2.3.0+dfsg1-2+deb11u1vulnerable
bullseye (security)2.3.0+dfsg1-2+deb11u3vulnerable
bookworm2.11.7+dfsg1-6~deb12u1vulnerable
freerdp3 (PTS)trixie3.15.0+dfsg-2.1+deb13u3vulnerable
forky, sid3.30.0+dfsg-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
freerdp2source(unstable)(unfixed)
freerdp3source(unstable)3.28.0+dfsg-1

Notes

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pjqx-v446-x7fc

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