Linux Kernel up to 7.3.2 xen-netback xenvif_mcast_addr_list_free race condition

CVSS Meta Temp Score
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CTI Interest Score
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9.5$0-$5k3.15-

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.3.2 and classified as very critical. This vulnerability affects the function xenvif_mcast_addr_list_free of the component xen-netback. The manipulation results in race condition. This vulnerability is reported as CVE-2026-100081. The attack can be launched remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 7.3.2. Affected is the function xenvif_mcast_addr_list_free of the component xen-netback. The manipulation with an unknown input leads to a race condition vulnerability. CWE is classifying the issue as CWE-362. The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: xen-netback: defer xenvif_mcast_addr_list_free() In order for the function to legitimately avoid locking/RCU, it needs to run after all TX/RX processing has finished/stopped: Lookups happen from xenvif_start_xmit(), while adds/removes happen from xenvif_tx_action() (called out of xenvif_poll()). Move the call out of xenvif_disconnect_data() (the call to the function from connect()'s error path doesn't require any cleaning up there), and put it past the synchronization point in backend_disconnect(). This is XSA-527 / CVE-2026-100081.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-100081 since 09/25/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 11/06/2026).

Upgrading to version 5.10.274, 5.15.225, 6.1.192, 6.6.162, 6.12.116, 6.18.62 or 7.3.3 eliminates this vulnerability. Applying the patch 96e05a8ce243e2207704e2e7a6e7d1172730f515/0e786123e46d08d2247ce93a5435e45ed9f4c5d1/990d123d9eaa3ac6c979eed245658676d65ce0db/0d515c409033c8e2a645a781be3ca76ab825fc8c/a6bb2f1fa62c56279bdcdadce28d1310c5e12b62/34f0f63dc6dc11895a17bb5672451b6b11622c99/fb38fc58acb26d74fe8f7b19621fafaae3c040ff is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
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: Race condition
CWE: CWE-362
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: Kernel 5.10.274/5.15.225/6.1.192/6.6.162/6.12.116/6.18.62/7.3.3
Patch: 96e05a8ce243e2207704e2e7a6e7d1172730f515/0e786123e46d08d2247ce93a5435e45ed9f4c5d1/990d123d9eaa3ac6c979eed245658676d65ce0db/0d515c409033c8e2a645a781be3ca76ab825fc8c/a6bb2f1fa62c56279bdcdadce28d1310c5e12b62/34f0f63dc6dc11895a17bb5672451b6b11622c99/fb38fc58acb26d74fe8f7b19621fafaae3c040ff

Timelineinfo

09/25/2026 CVE reserved
11/06/2026 +42 days Advisory disclosed
11/06/2026 +0 days VulDB entry created
11/06/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CNA: Linux
CVE: CVE-2026-100081 (🔒)

GCVE (CVE): GCVE-0-2026-100081
GCVE (VulDB): GCVE-100-432072

Entryinfo

Created: 11/06/2026 19:43
Changes: 11/06/2026 19:43 (59)
Complete: 🔍
Cache ID: 216::103

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