Linux Kernel up to 7.3-rc4 cls_u32 net/sched/cls_u32.c handle2id memory leak

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7.4	$0-$5k	2.28

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.3-rc4 and classified as critical. This issue affects the function handle2id of the file net/sched/cls_u32.c of the component cls_u32. The manipulation results in memory leak. This vulnerability was named CVE-2026-98629. The attack needs to be approached locally. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 7.3-rc4. Affected is the function handle2id of the file net/sched/cls_u32.c of the component cls_u32. The manipulation with an unknown input leads to a memory leak vulnerability. CWE is classifying the issue as CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: fix manual hash table handle IDR aliasing A u32 hash table created with an explicit handle ('tc filter add ... handle 801: u32 divisor N') keys its IDR entry on the raw handle, while the destroy paths free it under handle2id(handle). The two key domains disagree for handles in the 0x800..0xFFF htid range: handle2id() folds them back into the auto-allocated id space (1..0x7FF). A manual table therefore leaves its raw-keyed IDR entry unreachable on delete (a permanent leak), and its delete can drop the idr entry of an unrelated live auto table. A later auto allocation can then hand out a handle that aliases the live manual table; u32_lookup_ht() first-match routes lookups and TCA_U32_LINK for that htid to the wrong table. Key the divisor-path alloc on handle2id(handle) so allocation and removal share one key domain. A manual handle that maps onto an id already in use is rejected with -ENOSPC, and auto allocation skips ids held by live manual tables. Conditions to recreate: ip link add test0 type dummy tc qdisc add dev test0 clsact tc filter add dev test0 ingress protocol ip pref 1 \ handle 801: u32 divisor 16 tc filter add dev test0 ingress protocol ip pref 2 u32 divisor 16 tc -d filter show dev test0 ingress | grep 'fh 801:' # unpatched: two live tables with handle 0x80100000 (the pref 2 root # hnode is auto-allocated id 1); patched: the auto hnode takes id 2. Also tested with a poc with a live u32 table on the block, add/delete a manual table 'handle 901: u32 divisor 1' twice; unpatched, the re-add fails with -ENOSPC because the raw key leaked on the first delete.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-98629 since 09/25/2026. The exploitability is told to be easy. Local access is required to approach this attack. Additional levels of successful authentication are necessary for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3-rc5 eliminates this vulnerability. Applying the patch 21fc07924e996e1e661268ca269c86b8d59d25b3/0fac292d93fdb313099e98cce928b3a524c92c94/54a454c5e41f5e2cb70c8163140ce095c5d5eefd/f6696481eedfd5752b4b56eed715d0b0fe48b9c5/2f898f9ec7c73c5697ee462681e7ea6984ee1f3d/0a5f5d9e94dead312d32c366b917c64e552b72f7 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.188
• 6.6.157
• 6.12.111
• 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
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 6.18.50
• 6.18.51
• 6.18.52
• 6.18.53
• 6.18.54
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.3-rc1
• 7.3-rc2
• 7.3-rc3
• 7.3-rc4

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
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CPE 2.2info

• 🔒
• 🔒
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CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.7
VulDB Meta Temp Score: 7.4

VulDB Base Score: 7.7
VulDB Temp Score: 7.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory leak
CWE: CWE-401 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

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 6.1.189/6.6.158/6.12.112/6.18.55/7.2.9/7.3-rc5
Patch: 21fc07924e996e1e661268ca269c86b8d59d25b3/0fac292d93fdb313099e98cce928b3a524c92c94/54a454c5e41f5e2cb70c8163140ce095c5d5eefd/f6696481eedfd5752b4b56eed715d0b0fe48b9c5/2f898f9ec7c73c5697ee462681e7ea6984ee1f3d/0a5f5d9e94dead312d32c366b917c64e552b72f7

Timelineinfo

09/25/2026 CVE reserved
10/18/2026 +23 days Advisory disclosed
10/18/2026 +0 days VulDB entry created
10/18/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98629 (🔒)
GCVE (CVE): GCVE-0-2026-98629
GCVE (VulDB): GCVE-100-422118

Entryinfo

Created: 10/18/2026 20:29
Changes: 10/18/2026 20:29 (60)
Complete: 🔍
Cache ID: 216::103

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