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VulnerabilityPublished Updated

CVE-2024-56617: Linux kernel · cacheinfo: Allocate memory during CPU hotplug if not done from the primary CPU

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 5.5 Medium · fixed in 6.11.0-1012.12~24.04.1 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.11.0-1012.12~24.04.1, 6.11.0-1011.11~24.04.1, 6.11.0-21.21~24.04.1 +2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Dec 2024

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux@6.8.0-136.136?arch=source&distro=nobleOther threatsAffected
  • 6.5.0-9.9 – 6.8.0-136.136
53 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@6.8.0-1060.63?arch=source&distro=nobleOther threatsAffected
  • 6.5.0-1008.8 – 6.8.0-1060.63
48 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@6.8.0-1062.69?arch=source&distro=nobleOther threatsAffected
  • 6.5.0-1007.7 – 6.8.0-1062.69
39 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11@6.11.0-1012.12~24.04.1?arch=source&distro=nobleOther threatsAffected
  • <6.11.0-1012.12~24.04.1
Fixed in
  • 6.11.0-1012.12~24.04.1
Ubuntu 24.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.8.0-1061.68?arch=source&distro=nobleOther threatsAffected
  • 6.8.0-1041.48 – 6.8.0-1061.68
6 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia@6.8.0-1039.42?arch=source&distro=nobleOther threatsAffected
  • 6.8.0-1013.14 – 6.8.0-1039.42
10 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

In the Linux kernel, the following vulnerability has been resolved: cacheinfo: Allocate memory during CPU hotplug if not done from the primary CPU Commit 5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU") adds functionality that architectures can use to optionally allocate and build cacheinfo early during boot. Commit 6539cffa9495 ("cacheinfo: Add arch specific early level initializer") lets secondary CPUs correct (and reallocate memory) cacheinfo data if needed. If the early build functionality is not used and cacheinfo does not need correction, memory for cacheinfo is never allocated. x86 does not use the early build functionality. Consequently, during the cacheinfo CPU hotplug callback, last_level_cache_is_valid() attempts to dereference a NULL pointer: BUG: kernel NULL pointer dereference, address: 0000000000000100 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not present page PGD 0 P4D 0 Oops: 0000 [#1] PREEPMT SMP NOPTI CPU: 0 PID 19 Comm: cpuhp/0 Not tainted 6.4.0-rc2 #1 RIP: 0010: last_level_cache_is_valid+0x95/0xe0a Allocate memory for cacheinfo during the cacheinfo CPU hotplug callback if not done earlier. Moreover, before determining the validity of the last-level cache info, ensure that it has been allocated. Simply checking for non-zero cache_leaves() is not sufficient, as some architectures (e.g., Intel processors) have non-zero cache_leaves() before allocation. Dereferencing NULL cacheinfo can occur in update_per_cpu_data_slice_size(). This function iterates over all online CPUs. However, a CPU may have come online recently, but its cacheinfo may not have been allocated yet. While here, remove an unnecessary indentation in allocate_cache_info(). [ bp: Massage. ]

References

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