Linux Kernel up to 7.1.9 cls_u32 net/sched/cls_u32.c tc_cls_bind_class fh out-of-bounds

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.5	$0-$5k	0.61-

Summaryinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 6.1.183/6.6.152/6.12.104/6.18.45/7.1.9. This affects the function tc_cls_bind_class of the file net/sched/cls_u32.c of the component cls_u32. Performing a manipulation of the argument fh results in out-of-bounds. This vulnerability was named CVE-2026-74739. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 6.1.183/6.6.152/6.12.104/6.18.45/7.1.9. This affects the function tc_cls_bind_class of the file net/sched/cls_u32.c of the component cls_u32. The manipulation of the argument fh with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: skip hash tables in u32_bind_class() u32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode through the walker callback. u32_bind_class() unconditionally casts the passed fh to tc_u_knode and accesses &n->res, so when fh is actually a tc_u_hnode, which has no tcf_result member, this results in a slab-out-of-bounds read of res->classid in tc_cls_bind_class(). The issue can be reproduced with the following commands: tc qdisc add dev lo root handle 1: hfsc tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1 tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit Fix this by skipping hash tables via the TC_U32_KEY(handle) check.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-74739 since 08/15/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Additional levels of successful authentication are necessary for exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/26/2026).

Upgrading to version 6.1.184, 6.6.153, 6.12.105, 6.18.46 or 7.1.10 eliminates this vulnerability. Applying the patch ec5f3005586a785689fd568361b0c5925cb1548b/19d114b93c94bdef70496f26685c2a6b242f41b3/594a064d603202b9ee21e07679d854e5c1750cc4/31f26a95eeee926946809ac456c61a3217936a62/e71f8e9ed6f311410b14741f6012afe01869c0fa/6d3724e616faf952c3adcf8414fc21a828ef3709 is able to eliminate this problem.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.183
• 6.6.152
• 6.12.104
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4
• 7.1.5
• 7.1.6
• 7.1.7
• 7.1.8
• 7.1.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.7
VulDB Meta Temp Score: 4.5

VulDB Base Score: 4.7
VulDB Temp Score: 4.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.184/6.6.153/6.12.105/6.18.46/7.1.10
Patch: ec5f3005586a785689fd568361b0c5925cb1548b/19d114b93c94bdef70496f26685c2a6b242f41b3/594a064d603202b9ee21e07679d854e5c1750cc4/31f26a95eeee926946809ac456c61a3217936a62/e71f8e9ed6f311410b14741f6012afe01869c0fa/6d3724e616faf952c3adcf8414fc21a828ef3709

Timelineinfo

08/15/2026 CVE reserved
08/26/2026 +11 days Advisory disclosed
08/26/2026 +0 days VulDB entry created
08/26/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74739 (🔒)
GCVE (CVE): GCVE-0-2026-74739
GCVE (VulDB): GCVE-100-395793

Entryinfo

Created: 08/26/2026 16:58
Changes: 08/26/2026 16:58 (61)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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