CVE-2026-84894Network attack vector

Invalid memory access via stale WebTransport handle

Published Sep 28, 2026 · Updated Sep 28, 2026

Use-after-free in Meta Platforms, Inc. moxygen before 004123dd24c3 allows remote attackers to trigger invalid memory access via a MoQT data stream. MoQSession::dataStreamReadLoop retains a WebTransport read handle after a FIN-bearing read invalidates it, then uses that stale handle while processing an unknown track alias. Exploitation requires a peer to send the unknown alias and FIN in the same write; the public patch does not establish code execution or data disclosure.

CVSS severityUnavailable
Unscored
EPSS probability0.26%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Meta Platforms, Inc. moxygen before 004123dd24c3 allows remote attackers to trigger invalid memory access via a MoQT data stream. MoQSession::dataStreamReadLoop retains a WebTransport read handle after a FIN-bearing read invalidates it, then uses that stale handle while processing an unknown track alias. Exploitation requires a peer to send the unknown alias and FIN in the same write; the public patch does not establish code execution or data disclosure.

The record

CVE
CVE-2026-84894
Published
Sep 28, 2026
Updated
Sep 28, 2026
Vendor
Meta Platforms, Inc.
Product
moxygen
Classifications
T1499.004
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 28, 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?

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  1. Affected versionversion=b24f8e65cb83ebe5f3880cc4e3a4c8f64e1882f9 <004123dd24c30dad6b649163575145f240dabc94

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Meta Platforms, Inc. · moxygenversion=b24f8e65cb83ebe5f3880cc4e3a4c8f64e1882f9 <004123dd24c30dad6b649163575145f240dabc94

Published CVSS scores

No CVSS assessment is available in this record.

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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