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CVE Record

CVE-2024-36916: blk-iocost: avoid out of bounds shift

In the Linux kernel, the following vulnerability has been resolved: blk-iocost: avoid out of bounds shift UBSAN catches undefined behavior in blk-iocost, where sometimes iocg->delay is shifted right by a number that is too large, resulting in undefined behavior on some architectures. [ 186.556576] ------------[ cut here ]------------ UBSAN: shift-out-of-bounds in block/blk-iocost.c:1366:23 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long') CPU: 16 PID: 0 Comm: swapper/16 Tainted: G S E N 6.9.0-0_fbk700_debug_rc2_kbuilder_0_gc85af715cac0 #1 Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A23 12/08/2020 Call Trace: <IRQ> dump_stack_lvl+0x8f/0xe0 __ubsan_handle_shift_out_of_bounds+0x22c/0x280 iocg_kick_delay+0x30b/0x310 ioc_timer_fn+0x2fb/0x1f80 __run_timer_base+0x1b6/0x250 ... Avoid that undefined behavior by simply taking the "delay = 0" branch if the shift is too large. I am not sure what the symptoms of an undefined value delay will be, but I suspect it could be more than a little annoying to debug.

MediumCVSS 6.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2024-36916 is a Linux kernel bug in the block I/O cost controller. Under some conditions, the kernel shifts a delay value too far, causing undefined behavior. The public record rates it medium, with possible integrity and availability impact, but the sources do not show confirmed exploitation.

Executive priority

Handle through normal kernel patch governance, with higher priority for shared infrastructure, storage-heavy systems, and appliances named by vendor advisories. There is no supplied evidence of active exploitation, so this is not an emergency on that basis alone.

Technical view

The flaw is in block/blk-iocost.c, where iocg->delay can be right-shifted by an exponent too large for a 64-bit value. UBSAN reports shift-out-of-bounds in iocg_kick_delay. The kernel fix takes the delay=0 branch when the shift is too large.

Likely exposure

Exposure is most likely on systems running affected Linux kernel lines or downstream products that embed those kernels. The source bundle lists Linux versions including 5.10 through 6.9 ranges and vendor advisories from Debian, NetApp, and Siemens.

Exploitation context

The CVE is not listed as KEV, and the supplied sources do not claim active exploitation. The public evidence describes a kernel undefined-behavior condition rather than a public exploit path. Treat exploitability details as incomplete.

Researcher notes

The main uncertainty is practical impact. The upstream note says symptoms of the undefined delay value were unclear. Validation should focus on affected kernel lineage, runtime evidence of UBSAN reports, and whether downstream vendor fixes have landed.

Mitigation direction

  • Update affected Linux kernels to vendor-fixed versions.
  • Follow Debian LTS guidance where Debian kernels are in use.
  • Check NetApp and Siemens advisories for product-specific applicability.
  • Track kernel stable fixes referenced by the CVE record.
  • Avoid relying on unverified workarounds; use vendor guidance.

Validation and detection

  • Inventory running kernel versions across servers and appliances.
  • Compare versions against vendor advisories and kernel stable fixes.
  • Review kernel logs for UBSAN shift-out-of-bounds reports in blk-iocost.
  • Check whether affected systems use blk-iocost or related I/O control features.
  • Confirm downstream vendor firmware or OS images include the fix.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2024-36916 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
3ADP providers
11Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
6.5CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L3.92.5CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

6.5Medium
CVSS 3.1 vector shape for CVE-2024-36916Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux5160a5a53c0c4ae3708959d9465ea43ad5d90542, 5160a5a53c0c4ae3708959d9465ea43ad5d90542, 5160a5a53c0c4ae3708959d9465ea43ad5d90542, 5160a5a53c0c4ae3708959d9465ea43ad5d90542, 5160a5a53c0c4ae3708959d9465ea43ad5d90542, 5160a5a53c0c4ae3708959d9465ea43ad5d90542unaffected
LinuxLinux5.10, 0, 5.10.217, 5.15.159, 6.1.91, 6.6.31, 6.8.10, 6.9affected
Weakness

CWE details

No CWE listed

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