CVE-2026-33977: freerdp Reachable Assertion

Vulnerability summary

CVE-2026-33977 is a medium (CVSS 6.9) Reachable Assertion vulnerability in freerdp. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 31.4% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 30-03-2026
   PublishedVulnerability first disclosed.
2. 31-03-2026
   Last modifiedVulnerability information updated.

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, a malicious RDP server can crash the FreeRDP client by sending audio data in IMA ADPCM format with an invalid initial step index value (>= 89). The unvalidated step index is read directly from the network and used to index into a 89-entry lookup table, triggering a WINPR_ASSERT() failure and process abort via SIGABRT. This affects any FreeRDP client that has audio redirection (RDPSND) enabled, which is the default configuration. This issue has been patched in version 3.24.2.

• CWE-617Reachable AssertionThe product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.