CVE-2021-46960Network attack vector

Kernel crash via positive key-lookup return

Published Feb 27, 2024 · Updated Aug 5, 2026

Improper error handling in affected Linux CIFS client branches allows remote attackers controlling an SMB server to crash the client kernel. The smb2_get_enc_key function returns positive 1 when a session-key lookup fails, so callers treat the failure as success and later dereference uninitialized result pointers. An SMB3 mount to a malicious or compromised server is required; a crafted transform PDU with an unknown SessionId can produce a kernel oops or panic.

CVSS severity7.5
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper error handling in affected Linux CIFS client branches allows remote attackers controlling an SMB server to crash the client kernel. The smb2_get_enc_key function returns positive 1 when a session-key lookup fails, so callers treat the failure as success and later dereference uninitialized result pointers. An SMB3 mount to a malicious or compromised server is required; a crafted transform PDU with an unknown SessionId can produce a kernel oops or panic.

The record

CVE
CVE-2021-46960
Published
Feb 27, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.11
  2. Affected versionversion=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <83728cbf366e334301091d5b808add468ab46b27
  3. Affected versionversion=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <93f3339b22ba17e66f0808737467b70ba087eaec
  4. Affected versionversion=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <aaa0faa5c28a91c362352d6b35dc3ed10df56fb0
  5. Affected versionversion=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <b399c1a3ea0b9d10047ff266d65533df7f15532f
  6. Affected versionversion=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <e486f8397f3f14a7cadc166138141fdb14379a54
  7. Affected versionversion=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <e94851629c49c65b4fbb29a5725ddfd7988f8f20
  8. Affected versionversion=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <f59a9242942fef0de7b926e438ba4eae65d4b4dd

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.11; version=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <83728cbf366e334301091d5b808add468ab46b27; version=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <93f3339b22ba17e66f0808737467b70ba087eaec; version=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <aaa0faa5c28a91c362352d6b35dc3ed10df56fb0; version=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <b399c1a3ea0b9d10047ff266d65533df7f15532f; version=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <e486f8397f3f14a7cadc166138141fdb14379a54; version=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <e94851629c49c65b4fbb29a5725ddfd7988f8f20; version=61cfac6f267dabcf2740a7ec8a0295833b28b5f5 <f59a9242942fef0de7b926e438ba4eae65d4b4dd

Published CVSS scores

7.5Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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