CVE-2026-64620
FreeRDP before 3.28.0 (affected <=3.27.1) contains a heap-based buffer overflow in crypto_rsa_common() (libfreerdp/crypto/crypto.c).
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.85%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 4.0
- 9.3 CRITICALCVSS: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/M
- EPSS
- 0.85% probability · 56th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-122
- Affected
- freerdp/freerdp
- Source
- disclosure@vulncheck.com
References
- https://github.com/FreeRDP/FreeRDP/commit/1f7a716d39b5605bb8a83b0c3c97a6ce386609efPatch
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pjqx-v446-x7fcExploit, Mitigation, Vendor Advisory
- https://www.vulncheck.com/advisories/freerdp-before-heap-buffer-overflow-via-crypto-rsa-commonPatch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.