Linux Kernel: Use-After-Free (CVE-2024-53166)
Published Last modified Sources: Siemens ProductCERT, SUSE, Red Hat, Debian LTS, Debian, BSI, Msrc Update Guide, CVE.org, EUVD
What is affected, what to do
In the Linux kernel, the following vulnerability has been resolved: block, bfq: fix bfqq uaf in bfq_limit_depth() Set new allocated bfqq to bic or remove freed bfqq from bic are both protected by bfqd->lock, however bfq_limit_depth() is deferencing bfqq from bic without the lock, this can lead to UAF if the io_context is shared by multiple tasks. For example, test bfq with io_uring can trigger following UAF in v6.6: ================================================================== BUG: KASAN: slab-use-after-free in bfqq_group+0x15/0x50 Call Trace: <TASK> dump_stack_lvl+0x47/0x80 print_address_description.constprop.0+0x66/0x300 print_report+0x3e/0x70 kasan_report+0xb4/0xf0 bfqq_group+0x15/0x50 bfqq_request_over_limit+0x130/0x9a0 bfq_limit_depth+0x1b5/0x480 __blk_mq_alloc_requests+0x2b5/0xa00 blk_mq_get_new_requests+0x11d/0x1d0 blk_mq_submit_bio+0x286/0xb00 submit_bio_noacct_nocheck+0x331/0x400 __block_write_full_folio+0x3d0/0x640 writepage_cb+0x3b/0xc0 write_cache_pages+0x254/0x6c0 write_cache_pages+0x254/0x6c0 do_writepages+0x192/0x310 filemap_fdatawrite_wbc+0x95/0xc0 __filemap_fdatawrite_range+0x99/0xd0 filemap_write_and_wait_range.part.0+0x4d/0xa0 blkdev_read_iter+0xef/0x1e0 io_read+0x1b6/0x8a0 io_issue_sqe+0x87/0x300 io_wq_submit_work+0xeb/0x390 io_worker_handle_work+0x24d/0x550 io_wq_worker+0x27f/0x6c0 ret_from_fork_asm+0x1b/0x30 </TASK> Allocated by task 808602: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 __kasan_slab_alloc+0x83/0x90 kmem_cache_alloc_node+0x1b1/0x6d0 bfq_get_queue+0x138/0xfa0 bfq_get_bfqq_handle_split+0xe3/0x2c0 bfq_init_rq+0x196/0xbb0 bfq_insert_request.isra.0+0xb5/0x480 bfq_insert_requests+0x156/0x180 blk_mq_insert_request+0x15d/0x440 blk_mq_submit_bio+0x8a4/0xb00 submit_bio_noacct_nocheck+0x331/0x400 __blkdev_direct_IO_async+0x2dd/0x330 blkdev_write_iter+0x39a/0x450 io_write+0x22a/0x840 io_issue_sqe+0x87/0x300 io_wq_submit_work+0xeb/0x390 io_worker_handle_work+0x24d/0x550 io_wq_worker+0x27f/0x6c0 ret_from_fork+0x2d/0x50 ret_from_fork_asm+0x1b/0x30 Freed by task 808589: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x27/0x40 __kasan_slab_free+0x126/0x1b0 kmem_cache_free+0x10c/0x750 bfq_put_queue+0x2dd/0x770 __bfq_insert_request.isra.0+0x155/0x7a0 bfq_insert_request.isra.0+0x122/0x480 bfq_insert_requests+0x156/0x180 blk_mq_dispatch_plug_list+0x528/0x7e0 blk_mq_flush_plug_list.part.0+0xe5/0x590 __blk_flush_plug+0x3b/0x90 blk_finish_plug+0x40/0x60 do_writepages+0x19d/0x310 filemap_fdatawrite_wbc+0x95/0xc0 __filemap_fdatawrite_range+0x99/0xd0 filemap_write_and_wait_range.part.0+0x4d/0xa0 blkdev_read_iter+0xef/0x1e0 io_read+0x1b6/0x8a0 io_issue_sqe+0x87/0x300 io_wq_submit_work+0xeb/0x390 io_worker_handle_work+0x24d/0x550 io_wq_worker+0x27f/0x6c0 ret_from_fork+0x2d/0x50 ret_from_fork_asm+0x1b/0x30 Fix the problem by protecting bic_to_bfqq() with bfqd->lock.
Update Linux Kernel to version 6.1.130, Linux Kernel to version 6.6.64, Linux Kernel to version 6.11.11.
- Affected
- Linux Kernel
lt 5.17..6.1.130 - Linux Kernel
lt 6.2..6.6.64 - Linux Kernel
lt 6.7..6.11.11 - Linux Kernel
lt 6.12..6.12.2
- Linux Kernel
- Fixed in
- Linux Kernel
6.1.130 - Linux Kernel
6.6.64 - Linux Kernel
6.11.11 - Linux Kernel
6.12.2 - Linux Kernel
6.13
- Linux Kernel
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Metrics
7.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
7.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: Siemens ProductCERT, SUSE, Red Hat, Debian LTS, Debian, BSI, Msrc Update Guide, CVE.org, EUVD
0.3 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 17.4
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 48.71 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 7.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 7.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.3 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 17.4
- Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
- CISA assessment (SSVC)
- Exploitation: none known · not automatable · Technical impact: total
- Source: CISA Vulnrichment, as of 10 February 2025
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-416
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
In the Linux kernel, the following vulnerability has been resolved: block, bfq: fix bfqq uaf in bfq_limit_depth() Set new allocated bfqq to bic or remove freed bfqq from bic are both protected by bfqd->lock, however bfq_limit_depth() is deferencing bfqq from bic without the lock, this can lead to UAF if the io_context is shared by multiple tasks. For example, test bfq with io_uring can trigger following UAF in v6.6: ================================================================== BUG: KASAN: slab-use-after-free in bfqq_group+0x15/0x50 Call Trace: <TASK> dump_stack_lvl+0x47/0x80 print_address_description.constprop.0+0x66/0x300 print_report+0x3e/0x70 kasan_report+0xb4/0xf0 bfqq_group+0x15/0x50 bfqq_request_over_limit+0x130/0x9a0 bfq_limit_depth+0x1b5/0x480 __blk_mq_alloc_requests+0x2b5/0xa00 blk_mq_get_new_requests+0x11d/0x1d0 blk_mq_submit_bio+0x286/0xb00 submit_bio_noacct_nocheck+0x331/0x400 __block_write_full_folio+0x3d0/0x640 writepage_cb+0x3b/0xc0 write_cache_pages+0x254/0x6c0 write_cache_pages+0x254/0x6c0 do_writepages+0x192/0x310 filemap_fdatawrite_wbc+0x95/0xc0 __filemap_fdatawrite_range+0x99/0xd0 filemap_write_and_wait_range.part.0+0x4d/0xa0 blkdev_read_iter+0xef/0x1e0 io_read+0x1b6/0x8a0 io_issue_sqe+0x87/0x300 io_wq_submit_work+0xeb/0x390 io_worker_handle_work+0x24d/0x550 io_wq_worker+0x27f/0x6c0 ret_from_fork_asm+0x1b/0x30 </TASK> Allocated by task 808602: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 __kasan_slab_alloc+0x83/0x90 kmem_cache_alloc_node+0x1b1/0x6d0 bfq_get_queue+0x138/0xfa0 bfq_get_bfqq_handle_split+0xe3/0x2c0 bfq_init_rq+0x196/0xbb0 bfq_insert_request.isra.0+0xb5/0x480 bfq_insert_requests+0x156/0x180 blk_mq_insert_request+0x15d/0x440 blk_mq_submit_bio+0x8a4/0xb00 submit_bio_noacct_nocheck+0x331/0x400 __blkdev_direct_IO_async+0x2dd/0x330 blkdev_write_iter+0x39a/0x450 io_write+0x22a/0x840 io_issue_sqe+0x87/0x300 io_wq_submit_work+0xeb/0x390 io_worker_handle_work+0x24d/0x550 io_wq_worker+0x27f/0x6c0 ret_from_fork+0x2d/0x50 ret_from_fork_asm+0x1b/0x30 Freed by task 808589: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x27/0x40 __kasan_slab_free+0x126/0x1b0 kmem_cache_free+0x10c/0x750 bfq_put_queue+0x2dd/0x770 __bfq_insert_request.isra.0+0x155/0x7a0 bfq_insert_request.isra.0+0x122/0x480 bfq_insert_requests+0x156/0x180 blk_mq_dispatch_plug_list+0x528/0x7e0 blk_mq_flush_plug_list.part.0+0xe5/0x590 __blk_flush_plug+0x3b/0x90 blk_finish_plug+0x40/0x60 do_writepages+0x19d/0x310 filemap_fdatawrite_wbc+0x95/0xc0 __filemap_fdatawrite_range+0x99/0xd0 filemap_write_and_wait_range.part.0+0x4d/0xa0 blkdev_read_iter+0xef/0x1e0 io_read+0x1b6/0x8a0 io_issue_sqe+0x87/0x300 io_wq_submit_work+0xeb/0x390 io_worker_handle_work+0x24d/0x550 io_wq_worker+0x27f/0x6c0 ret_from_fork+0x2d/0x50 ret_from_fork_asm+0x1b/0x30 Fix the problem by protecting bic_to_bfqq() with bfqd->lock.
Source: siemens_advisory, suse_csaf, redhat_csaf, Debian LTS Advisories, Debian Security Advisories, BSI CSAF, BSI WID Portal, Microsoft Security Update Guide, cvelistv5, NVD (NIST), CVE.org (MITRE), ENISA EUVD
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Linux | Linux |
|
|
| Siemens | SIMATIC S7 |
|
|
Vendors and products
Affected operating systems
| Linux | debian | linux | bookworm |
| Linux | debian | linux-6.1 | bullseye |
| Linux | linux | linux_kernel | — |
Weakness classes (CWE)
CWE-416Use After Free
Variant
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Entry at MITRE CWE-416
References & sources
- git.kernel.orgstable/c/ada4ca5fd5a9d5212f28164d49a4885951c979c9
- git.kernel.orgstable/c/906cdbdd3b018ff69cc830173bce277a847d4fdc
- git.kernel.orgstable/c/dcaa738afde55085ac6056252e319479cf23cde2
- git.kernel.orgstable/c/01a853faaeaf3379ccf358ade582b1d28752126e
- git.kernel.orgstable/c/e8b8344de3980709080d86c157d24e7de07d70ad
- lists.debian.orgdebian-lts-announce/2025/05/msg00045.html
- Siemens ProductCERTproductcert/html/ssa-082556.html
- Siemens ProductCERTproductcert/html/ssa-784472.html
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedLinux
CVSS V3.1: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
New references:- https://git.kernel.org/stable/c/01a853faaeaf3379ccf358ade582b1d28752126e
- https://git.kernel.org/stable/c/906cdbdd3b018ff69cc830173bce277a847d4fdc
- https://git.kernel.org/stable/c/ada4ca5fd5a9d5212f28164d49a4885951c979c9
- https://git.kernel.org/stable/c/dcaa738afde55085ac6056252e319479cf23cde2
and 1 more reference
Show 15 original changes
Individual changes of this event as published by NVD Type Action Before After CVSS added —AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HReference added —https://git.kernel.org/stable/c/01a853faaeaf3379ccf358ade582b1d28752126eReference added —https://git.kernel.org/stable/c/906cdbdd3b018ff69cc830173bce277a847d4fdcReference added —https://git.kernel.org/stable/c/ada4ca5fd5a9d5212f28164d49a4885951c979c9Reference added —https://git.kernel.org/stable/c/dcaa738afde55085ac6056252e319479cf23cde2Reference added —https://git.kernel.org/stable/c/e8b8344de3980709080d86c157d24e7de07d70adReference removed https://git.kernel.org/stable/c/01a853faaeaf3379ccf358ade582b1d28752126e—Reference removed https://git.kernel.org/stable/c/906cdbdd3b018ff69cc830173bce277a847d4fdc—Reference removed https://git.kernel.org/stable/c/ada4ca5fd5a9d5212f28164d49a4885951c979c9—Reference removed https://git.kernel.org/stable/c/dcaa738afde55085ac6056252e319479cf23cde2—Reference removed https://git.kernel.org/stable/c/e8b8344de3980709080d86c157d24e7de07d70ad—Reference type removed https://git.kernel.org/stable/c/01a853faaeaf3379ccf358ade582b1d28752126e Types: Patch—Reference type removed https://git.kernel.org/stable/c/906cdbdd3b018ff69cc830173bce277a847d4fdc Types: Patch—Reference type removed https://git.kernel.org/stable/c/dcaa738afde55085ac6056252e319479cf23cde2 Types: Patch—Reference type removed https://git.kernel.org/stable/c/e8b8344de3980709080d86c157d24e7de07d70ad Types: Patch—Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Record modifiedCVE Program
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://lists.debian.org/debian-lts-announce/2025/05/msg00045.htmlReference removed https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html—Source identifier: af854a3a-2127-422b-91ae-364da2661108
Record modifiedSiemens ADP
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2024/53xxx/CVE-2024-53166.json">CVE-2024-53166</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-082556.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-784472.htmlReference removed https://cert-portal.siemens.com/productcert/html/ssa-082556.html—Source identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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<a href="https://intel.neosec.eu/en/cve/CVE-2024-53166"><img src="https://intel.neosec.eu/badge/cve/CVE-2024-53166.svg?lang=en" alt="CVE-2024-53166 – NEOSEC Intel" height="20"></a>