Vulnerability · Published Mar 30, 2026 · Assigned by GitHub_M
CVE-2026-33977FreeRDP: DoS via WINPR_ASSERT in IMA ADPCM audio decoder (dsp.c:331)
Medium 6.9
In plain English
A medium-severity security flaw in FreeRDP from FreeRDP. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 19% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | freerdp | 3.24.2-r0 | ALPINE-CVE-2026-33977 |
| Alpine:v3.24 | freerdp | 3.24.2-r0 | ALPINE-CVE-2026-33977 |
| Debian:12 | freerdp2 | no fix listed | DEBIAN-CVE-2026-33977 |
| Debian:13 | freerdp3 | 3.15.0+dfsg-2.1+deb13u2 | DEBIAN-CVE-2026-33977 |
| Debian:14 | freerdp3 | 3.24.2+dfsg-1 | DEBIAN-CVE-2026-33977 |
| Ubuntu:22.04:LTS | freerdp2 | no fix listed | UBUNTU-CVE-2026-33977 |
| Ubuntu:24.04:LTS | freerdp3 | 3.30.0+dfsg-0ubuntu0.24.04.1 | USN-8561-1 |
| Ubuntu:24.04:LTS | freerdp3 | 3.30.0+dfsg-0ubuntu0.24.04.1 | UBUNTU-CVE-2026-33977 |
| Ubuntu:25.10 | freerdp3 | no fix listed | UBUNTU-CVE-2026-33977 |
| Ubuntu:26.04:LTS | freerdp3 | 3.30.0+dfsg-0ubuntu0.26.04.1 | USN-8561-1 |
Affected products (as reported)
Weakness: CWE-617 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N