Linux Kernel up to 6.6.121/6.12.67/6.18.7/6.19-rc6 use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.7$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.6.121/6.12.67/6.18.7/6.19-rc6. This affects an unknown function. This manipulation causes use after free. This vulnerability is registered as CVE-2026-23074. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.121/6.12.67/6.18.7/6.19-rc6. It has been declared as critical. Affected by this vulnerability is an unknown functionality. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net/sched: Enforce that teql can only be used as root qdisc Design intent of teql is that it is only supposed to be used as root qdisc. We need to check for that constraint. Although not important, I will describe the scenario that unearthed this issue for the curious. GangMin Kim <[email protected]> managed to concot a scenario as follows: ROOT qdisc 1:0 (QFQ) ├── class 1:1 (weight=15, lmax=16384) netem with delay 6.4s └── class 1:2 (weight=1, lmax=1514) teql GangMin sends a packet which is enqueued to 1:1 (netem). Any invocation of dequeue by QFQ from this class will not return a packet until after 6.4s. In the meantime, a second packet is sent and it lands on 1:2. teql's enqueue will return success and this will activate class 1:2. Main issue is that teql only updates the parent visible qlen (sch->q.qlen) at dequeue. Since QFQ will only call dequeue if peek succeeds (and teql's peek always returns NULL), dequeue will never be called and thus the qlen will remain as 0. With that in mind, when GangMin updates 1:2's lmax value, the qfq_change_class calls qfq_deact_rm_from_agg. Since the child qdisc's qlen was not incremented, qfq fails to deactivate the class, but still frees its pointers from the aggregate. So when the first packet is rescheduled after 6.4 seconds (netem's delay), a dangling pointer is accessed causing GangMin's causing a UAF.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-23074 since 01/13/2026. The exploitation appears to be easy. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/01/2026).

The vulnerability scanner Nessus provides a plugin with the ID 297893 (Linux Distros Unpatched Vulnerability : CVE-2026-23074), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.122, 6.12.68, 6.18.8 or 6.19-rc7 eliminates this vulnerability. Applying the patch 0686bedfed34155520f3f735cbf3210cb9044380/4c7e8aa71c9232cba84c289b4b56cba80b280841/16ed73c1282d376b956bff23e5139add061767ba/50da4b9d07a7a463e2cfb738f3ad4cff6b2c9c3b is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (297893) and CERT Bund (WID-SEC-2026-0324). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Debian Linux
  • Google Cloud Platform
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Linux Kernel

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.8
NVD Vector: 🔒

CNA Base Score: 7.8
CNA Vector (Linux): 🔒

CVSSv2info

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

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 297893
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-23074

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.122/6.12.68/6.18.8/6.19-rc7
Patch: 0686bedfed34155520f3f735cbf3210cb9044380/4c7e8aa71c9232cba84c289b4b56cba80b280841/16ed73c1282d376b956bff23e5139add061767ba/50da4b9d07a7a463e2cfb738f3ad4cff6b2c9c3b

Timelineinfo

01/13/2026 CVE reserved
02/04/2026 +22 days Advisory disclosed
02/04/2026 +0 days VulDB entry created
07/01/2026 +146 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-23074 (🔒)
GCVE (CVE): GCVE-0-2026-23074
GCVE (VulDB): GCVE-100-344275
CERT Bund: WID-SEC-2026-0324 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 02/04/2026 17:47
Updated: 07/01/2026 01:41
Changes: 02/04/2026 17:47 (57), 02/05/2026 13:17 (1), 02/06/2026 08:31 (7), 02/07/2026 17:51 (2), 03/18/2026 22:51 (12), 04/30/2026 09:09 (1), 07/01/2026 01:41 (9)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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