CVE-2024-56681

Kernel memory corruption via ignored HMAC initialization failure

Published Dec 28, 2024 · Updated Aug 5, 2026

Use-after-free in the Broadcom SPU HMAC driver in affected Linux kernel builds allows local users to corrupt kernel memory through AF_ALG. ahash_hmac_init frees ctx->shash after a zero-length key makes ahash_init return -ENOKEY, but reports success and leaves the stale pointer for update or final operations. Any unprivileged local user with access to hmac-sha1-iproc can trigger the path, enabling kernel reads, writes, control-flow hijacking, or a panic.

CVSS severity7.8
High
EPSS probability0.24%
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 Broadcom SPU HMAC driver in affected Linux kernel builds allows local users to corrupt kernel memory through AF_ALG. ahash_hmac_init frees ctx->shash after a zero-length key makes ahash_init return -ENOKEY, but reports success and leaves the stale pointer for update or final operations. Any unprivileged local user with access to hmac-sha1-iproc can trigger the path, enabling kernel reads, writes, control-flow hijacking, or a panic.

The record

CVE
CVE-2024-56681
Published
Dec 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 28, 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=4.11
  2. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <05f0a3f5477ecaa1cf46448504afe9e7c2e96fcc
  3. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <19630cf57233e845b6ac57c9c969a4888925467b
  4. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <28f8ffa945f7d7150463e15097ea73b19529d6f5
  5. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <4ea3e3b761e371102bb1486778e2f8dbc9e37413
  6. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <75e1e38e5d80d6d9011b7322698ffba3dd3db30a
  7. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <8f1a9a960b1107bd0e0ec3736055f5ed0e717edf
  8. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <ae5253313e0ea5f00c06176074592b7f493c8546
  9. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <bba9e38c5ad41d0a88b22a59e5b6dd3e31825118
  10. Affected versionversion=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <ee36db8e8203420e6d5c42eb9428920c2fc36532

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=4.11; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <05f0a3f5477ecaa1cf46448504afe9e7c2e96fcc; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <19630cf57233e845b6ac57c9c969a4888925467b; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <28f8ffa945f7d7150463e15097ea73b19529d6f5; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <4ea3e3b761e371102bb1486778e2f8dbc9e37413; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <75e1e38e5d80d6d9011b7322698ffba3dd3db30a; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <8f1a9a960b1107bd0e0ec3736055f5ed0e717edf; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <ae5253313e0ea5f00c06176074592b7f493c8546; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <bba9e38c5ad41d0a88b22a59e5b6dd3e31825118; version=9d12ba86f818aa9cfe9f01b750336aa441f2ffa2 <ee36db8e8203420e6d5c42eb9428920c2fc36532

Published CVSS scores

4.4OracleCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/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
7.8Linux kernel CNACVSS:3.1/AV:L/AC:L/PR:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

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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