Invalid memory access via session closure callback
Published Sep 28, 2026 · Updated Sep 28, 2026
Use-after-free in Proxygen 2026.04.06.00 through versions before 2026.09.28.00 allows attackers to trigger invalid session-memory access. QuicWtSession::closeSession reads member fields after the base closeSession call notifies a handler that can release the session's last reference and destroy the object. The condition requires that final-reference release during closure; the available record does not establish remote reachability or a specific outcome beyond use-after-free.
Summary
What happened
Use-after-free in Proxygen 2026.04.06.00 through versions before 2026.09.28.00 allows attackers to trigger invalid session-memory access. QuicWtSession::closeSession reads member fields after the base closeSession call notifies a handler that can release the session's last reference and destroy the object. The condition requires that final-reference release during closure; the available record does not establish remote reachability or a specific outcome beyond use-after-free.
The record
- CVE
- CVE-2026-84895
- Published
- Sep 28, 2026
- Updated
- Sep 28, 2026
- Vendor
- Meta Platforms, Inc.
- Product
- Proxygen
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 28, 2026CVE publishedPublication date reported by the CVE source.
- 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=v2026.04.06.00 <v2026.09.28.00
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
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Technologies
Your stack
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Your stack
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