HighCVE-2026-17523

Linux Kernel: security vulnerability (CVE-2026-17523)

Published 27.07.2026Last modified 02.10.2026Sources: Red Hat, BSI, CVE.org

What is affected, what to do

In the Linux kernel, the following vulnerability has been resolved: can: bcm: switch timer to HRTIMER_MODE_SOFT and remove hrtimer_tasklet This patch switches the timer to HRTIMER_MODE_SOFT, which executed the timer callback in softirq context and removes the hrtimer_tasklet.

Update Linux Kernel to version 4.19.226, Linux Kernel to version 5.4.

Affected: Linux Kernel lt 2.6.29..4.19.226
Linux Kernel lt 4.20..5.4
Fixed in: Linux Kernel 4.19.226
Linux Kernel 5.4

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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: Red Hat, BSI, CVE.org

0.2 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 5.7

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: 60.69 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: 0.2 %; 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: 5.7; Low — this CVE sits in the lower 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: 27.07.2026
CISA assessment (SSVC): Exploitation: none known · not automatable · Technical impact: total; Source: CISA Vulnrichment, as of 27 July 2026

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

Source: redhat_csaf, BSI WID Portal, BSI CSAF, NVD (NIST), cvelistv5

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Linux	Linux	`4.20 – < 5.4` `2.6.29 – < 4.19.226`	`5.4` `4.19.226`
IBM	QRadar SIEM	`< 7.6.0.3` `<7.5.0 UP16 IF01`	`7.6.0.3` —
Open Source	Linux Kernel	`<5.4 with commit bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68` `<4.19.226 with commit 79305a826f872fe446c6fbf8450f515053ef6951`	— —

Vendors and products

Affected operating systems

Affected operating systems

Linux	linux	linux_kernel	`2.6.29`
Linux	linux	linux_kernel	—

References & sources

access.redhat.comRHSA-2026:55764Vendor advisory, x_refsource_REDHAT
access.redhat.comRHSA-2026:55765Vendor advisory, x_refsource_REDHAT
access.redhat.comRHSA-2026:61932Vendor advisory, x_refsource_REDHAT
access.redhat.comsecurity/cve/CVE-2026-17523Vulnerability database, x_refsource_REDHAT
bugzilla.redhat.comRHBZ#2507407Issue tracking, x_refsource_REDHAT
github.comtorvalds/linux/commit/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68
git.kernel.orgstable/c/79305a826f872fe446c6fbf8450f515053ef6951
git.kernel.orgstable/c/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68

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).

02.10.2026Initial analysis by NVDNVD

Newly listed as affected:

Linux Kernel (4.20 – before 5.4; 2.6.29.1 – before 4.19.226; 8 individual versions)

New references:

Show 4 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Weakness type (CWE)	added	—	NVD-CWE-noinfo
Product configuration	added	—	OR cpe:2.3:o:linux:linux_kernel:2.6.29:rc5::::::* cpe:2.3:o:linux:linux_kernel:2.6.29:rc3::::::* cpe:2.3:o:linux:linux_kernel:2.6.29:rc4::::::* cpe:2.3:o:linux:linux_kernel:2.6.29:rc7::::::* cpe:2.3:o:linux:linux_kernel:2.6.29:rc2::::::* cpe:2.3:o:linux:linux_kernel:2.6.29:rc8::::::* cpe:2.3:o:linux:linux_kernel:2.6.29:rc6::::::* cpe:2.3:o:linux:linux_kernel::::::::* versions from (including) 4.20 up to (excluding) 5.4 cpe:2.3:o:linux:linux_kernel:2.6.29:-::::::* cpe:2.3:o:linux:linux_kernel::::::::* versions from (including) 2.6.29.1 up to (excluding) 4.19.226
Reference type	added	—	kernel.org: https://git.kernel.org/stable/c/79305a826f872fe446c6fbf8450f515053ef6951 Types: Patch
Reference type	added	—	kernel.org: https://git.kernel.org/stable/c/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68 Types: Patch

Source identifier: nvd@nist.gov

10.09.2026Record modifiedLinux

1 individual change: Affected versions (publisher)

Show the original change

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/2026/17xxx/CVE-2026-17523.json">CVE-2026-17523</a>

Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

10.09.2026Record modifiedLinux
CVSS V3.1: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Show the original change
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:H
Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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:H

09.09.2026Record modifiedLinux

Description added or changed

New references:

Show 4 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	changed	A flaw was found in the Linux kernel in net/can/bcm.c in can: bcm, where an unprivileged local user can exploit this vulnerability to execute arbitrary code within the kernel, which leads to a local privilege escalation (LPE). This allows the attacker to gain root privileges and take full control of the affected system.	In the Linux kernel, the following vulnerability has been resolved: can: bcm: switch timer to HRTIMER_MODE_SOFT and remove hrtimer_tasklet This patch switches the timer to HRTIMER_MODE_SOFT, which executed the timer callback in softirq context and removes the hrtimer_tasklet.
Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/17xxx/CVE-2026-17523.json">CVE-2026-17523</a>
Reference	added	—	https://git.kernel.org/stable/c/79305a826f872fe446c6fbf8450f515053ef6951
Reference	added	—	https://git.kernel.org/stable/c/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68

Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

01.09.2026Record modifiedRed Hat

New references:

and 2 more references

Show 12 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/2026/17xxx/CVE-2026-17523.json">CVE-2026-17523</a>
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55764
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55765
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:61932
Reference	added	—	https://access.redhat.com/security/cve/CVE-2026-17523
Reference	added	—	https://bugzilla.redhat.com/show_bug.cgi?id=2507407
Reference	added	—	https://github.com/torvalds/linux/commit/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68
Reference	removed	https://access.redhat.com/errata/RHSA-2026:55764	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:55765	—
Reference	removed	https://access.redhat.com/security/cve/CVE-2026-17523	—
Reference	removed	https://bugzilla.redhat.com/show_bug.cgi?id=2507407	—
Reference	removed	https://github.com/torvalds/linux/commit/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68	—

Source identifier: secalert@redhat.com

Show 4 older changes

17.08.2026Record modifiedRed Hat

New references:

https://access.redhat.com/errata/RHSA-2026:55764

Show 2 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55764
Affected versions (publisher)	changed	Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6 (+5)	Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 10 (+5)

Source identifier: secalert@redhat.com

17.08.2026Record modifiedRed Hat

New references:

https://access.redhat.com/errata/RHSA-2026:55765

Show 2 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55765
Affected versions (publisher)	changed	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 (+5)	Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6 (+5)

Source identifier: secalert@redhat.com

29.07.2026Record modifiedRed Hat

Description added or changed

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	changed	A flaw was found in the kernel. An unprivileged local user can exploit this vulnerability to execute arbitrary code within the kernel, which leads to a local privilege escalation (LPE). This allows the attacker to gain root privileges and take full control of the affected system.	A flaw was found in the Linux kernel in net/can/bcm.c in can: bcm, where an unprivileged local user can exploit this vulnerability to execute arbitrary code within the kernel, which leads to a local privilege escalation (LPE). This allows the attacker to gain root privileges and take full control of the affected system.

Source identifier: secalert@redhat.com

27.07.2026ReceivedRed Hat

CVSS V3.1: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness type: CWE-825

Description added or changed

New references:

Show 7 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 (+5)
Description	added	—	A flaw was found in the kernel. An unprivileged local user can exploit this vulnerability to execute arbitrary code within the kernel, which leads to a local privilege escalation (LPE). This allows the attacker to gain root privileges and take full control of the affected system.
CVSS	added	—	AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness type (CWE)	added	—	CWE-825
Reference	added	—	https://access.redhat.com/security/cve/CVE-2026-17523
Reference	added	—	https://bugzilla.redhat.com/show_bug.cgi?id=2507407
Reference	added	—	https://github.com/torvalds/linux/commit/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68

Source identifier: secalert@redhat.com

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