CVE-2026-33977Public exploitNetwork attack vector

Client crash via unclamped ADPCM step index

Published Mar 30, 2026 · Updated Mar 30, 2026

Reachable assertion in FreeRDP before 3.24.2 allows remote attackers controlling an RDP server to crash a connecting client via audio data. freerdp_dsp_decode_ima_adpcm loads an IMA ADPCM step index from the RDPSND payload and begins sample decoding before clamping it to the 89-entry table range. A user must connect with audio redirection enabled, the default, after which an index from 89 through 255 aborts the process without reported data disclosure or modification.

CVSS severity6.9
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in FreeRDP before 3.24.2 allows remote attackers controlling an RDP server to crash a connecting client via audio data. freerdp_dsp_decode_ima_adpcm loads an IMA ADPCM step index from the RDPSND payload and begins sample decoding before clamping it to the 89-entry table range. A user must connect with audio redirection enabled, the default, after which an index from 89 through 255 aborts the process without reported data disclosure or modification.

The record

CVE
CVE-2026-33977
Published
Mar 30, 2026
Updated
Mar 30, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.24.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 3.24.2

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.9GitHub, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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