CVE-2021-46973

Local privilege escalation via QRTR MHI send race

Published Feb 27, 2024 · Updated Aug 5, 2026

Use-after-free in the Linux kernel allows local users to escalate privileges through the QRTR MHI send path on supported Qualcomm systems. The qcom_mhi_qrtr_send function queues an skb before taking its socket reference, so an immediate MHI uplink callback can free the skb before the later dereference. An unprivileged local process must send on an AF_QIPCRTR socket to an MHI-backed remote QRTR node; exploitation can corrupt kernel memory or panic the host.

CVSS severity8.4
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel allows local users to escalate privileges through the QRTR MHI send path on supported Qualcomm systems. The qcom_mhi_qrtr_send function queues an skb before taking its socket reference, so an immediate MHI uplink callback can free the skb before the later dereference. An unprivileged local process must send on an AF_QIPCRTR socket to an MHI-backed remote QRTR node; exploitation can corrupt kernel memory or panic the host.

The record

CVE
CVE-2021-46973
Published
Feb 27, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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.

  1. Affected versionversion=5.8
  2. Affected versionversion=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <03c649dee8b1eb5600212a249542a70f47a5ab40
  3. Affected versionversion=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <47a017f33943278570c072bc71681809b2567b3a
  4. Affected versionversion=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <48ec949ac979b4b42d740f67b6177797af834f80
  5. Affected versionversion=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <ea474054c2cc6e1284604b21361f475c7cc8c0a0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.8; version=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <03c649dee8b1eb5600212a249542a70f47a5ab40; version=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <47a017f33943278570c072bc71681809b2567b3a; version=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <48ec949ac979b4b42d740f67b6177797af834f80; version=6e728f321393b1fce9e1c2c3e55f9f7c15991321 <ea474054c2cc6e1284604b21361f475c7cc8c0a0
The Linux Kernel Organization · Linux Kernelversion=5.8; version=6e728f321393 <=03c649dee8b1; version=6e728f321393 <47a017f33943; version=6e728f321393 <48ec949ac979; version=6e728f321393 <ea474054c2cc

Published CVSS scores

8.4CISA ADPCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

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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