Facebook Proxygen 2026.07.20.00 Quic Session closeSession use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.0$5k-$25k0.60

Summaryinfo

A vulnerability was found in Facebook Proxygen and classified as critical. The impacted element is the function QuicWtSession::closeSession of the component Quic Session. The manipulation results in use after free. This vulnerability was named CVE-2026-84895. The attack may be performed from remote. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Facebook Proxygen. It has been classified as critical. Affected is the function QuicWtSession::closeSession of the component Quic Session. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In proxygen from v2026.04.06.00 until v2026.09.28.00, QuicWtSession::closeSession accesses its member fields after calling the base QuicWtSessionBase::closeSession method. The base method notifies the session handler, which may release the last reference to the session and destroy it.

The advisory is available at facebook.com. This vulnerability is traded as CVE-2026-84895 since 09/02/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 09/28/2026).

Upgrading to version 2026.09.28.00 eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Proxygen 2026.09.28.00

Timelineinfo

09/02/2026 CVE reserved
09/28/2026 +26 days Advisory disclosed
09/28/2026 +0 days VulDB entry created
09/28/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: facebook.com
Status: Confirmed

CVE: CVE-2026-84895 (🔒)
GCVE (CVE): GCVE-0-2026-84895
GCVE (VulDB): GCVE-100-411198

Entryinfo

Created: 09/28/2026 23:12
Changes: 09/28/2026 23:12 (19), 09/28/2026 23:13 (37)
Complete: 🔍
Cache ID: 216::103

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