{"id":"CVE-2026-64620","summary":"FreeRDP before 3.28.0 Heap Buffer Overflow via crypto_rsa_common","details":"FreeRDP before 3.28.0 (affected \u003c=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 \u003e 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.","aliases":["GHSA-pjqx-v446-x7fc"],"modified":"2026-07-22T05:31:42.912714090Z","published":"2026-07-20T12:04:53.105Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-122"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64620.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64620.json"},{"type":"ADVISORY","url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pjqx-v446-x7fc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64620"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/freerdp-before-heap-buffer-overflow-via-crypto-rsa-common"},{"type":"FIX","url":"https://github.com/FreeRDP/FreeRDP/commit/1f7a716d39b5605bb8a83b0c3c97a6ce386609ef"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/freerdp/freerdp","events":[{"introduced":"0"},{"fixed":"5370fb26fbf034ecd11d3026b6ad639b5fff493f"},{"fixed":"1f7a716d39b5605bb8a83b0c3c97a6ce386609ef"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"3.28.0"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["3.5.1","3.5.0","3.4.0","3.3.0","3.2.0","3.1.0","3.0.0","3.0.0-rc0","3.0.0-beta4","3.0.0-beta3","3.0.0-beta2","3.0.0-beta1","2.0.0","2.0.0-rc4","2.0.0-rc3","2.0.0-rc2","2.0.0-rc1","2.0.0-rc0","2.0.0-beta1+android11","2.0.0-beta1+android10","1.2.0-beta1+android9","1.2.0-beta1+android7","1.1.0-beta+2013071101","1.1.0-beta1+ios4","1.1.0-beta1+android5","1.1.0-beta1+android4","1.1.0-beta1+ios3","1.1.0-beta1+ios2","1.1.0-beta1+android3","1.1.0-beta1+android2","1.1.0-beta1+ios1","1.1.0-beta1","1.0.1","1.0.0","1.0-beta5","1.0-beta4","1.0-beta2","1.0-beta1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64620.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"}]}