CVE-2026-91963Network attack vectorHinoki check available

Heap-memory disclosure via unwritten USB completions

Published Sep 15, 2026 · Updated Sep 15, 2026

Uninitialized-memory disclosure in the urbdrc channel before 3.31.0 allows remote attackers to read FreeRDP client heap data. urb_write_completion reserves OutputBufferSize bytes with Stream_Seek without writing or zeroing them before returning the completion PDU. USB redirection must be compiled and active with a redirected device; failed or short IN transfers expose stale pointers that defeat ASLR and enable code execution only when chained with a separate memory-corruption flaw.

CVSS severity7.5
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Uninitialized-memory disclosure in the urbdrc channel before 3.31.0 allows remote attackers to read FreeRDP client heap data. urb_write_completion reserves OutputBufferSize bytes with Stream_Seek without writing or zeroing them before returning the completion PDU. USB redirection must be compiled and active with a redirected device; failed or short IN transfers expose stale pointers that defeat ASLR and enable code execution only when chained with a separate memory-corruption flaw.

The record

CVE
CVE-2026-91963
Published
Sep 15, 2026
Updated
Sep 15, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-908, CWE-457, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <3.31.0
  2. Affected versionversion=2.0.0 <3.0.0
  3. Affected versionversion=3.0.0 <3.31.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=0 <3.31.0; version=2.0.0 <3.0.0; version=3.0.0 <3.31.0

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
CWE-457Use of Uninitialized Variable
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo