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CVE-2026-23413— clsact: Fix use-after-free in init/destroy rollback asymmetry

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于clsact qdisc初始化销毁不对称，可能导致释放后重用。

CVSS 7.8 · High EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 15

VendorProduct Version RangeStatus
Linux Linux 230bb13650b0f186f540500fd5f5f7096a822a2a< a73d95b57bf9faebdfed591bcb7ed9292062a84c affected
1cb6f0bae50441f4b4b32a28315853b279c7404e< 37bef86e5428d59f70a4da82b80f9a8f252fecbe affected
1cb6f0bae50441f4b4b32a28315853b279c7404e< 4c9af67f99aa3e51b522c54968ab3ac8272be41c affected
1cb6f0bae50441f4b4b32a28315853b279c7404e< 0509b762bc5e8ea7b8391130730c6d8502fc6e69 affected
1cb6f0bae50441f4b4b32a28315853b279c7404e< a0671125d4f55e1e98d9bde8a0b671941987e208 affected
f61ecf1bd5b562ebfd7d430ccb31619857e80857 affected
6.6.41< 6.6.130 affected
6.9.10< 6.10 affected
… +7 more rows
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I. Basic Information for CVE-2026-23413

Vulnerability Information
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Vulnerability Title
clsact: Fix use-after-free in init/destroy rollback asymmetry
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: clsact: Fix use-after-free in init/destroy rollback asymmetry Fix a use-after-free in the clsact qdisc upon init/destroy rollback asymmetry. The latter is achieved by first fully initializing a clsact instance, and then in a second step having a replacement failure for the new clsact qdisc instance. clsact_init() initializes ingress first and then takes care of the egress part. This can fail midway, for example, via tcf_block_get_ext(). Upon failure, the kernel will trigger the clsact_destroy() callback. Commit 1cb6f0bae504 ("bpf: Fix too early release of tcx_entry") details the way how the transition is happening. If tcf_block_get_ext on the q->ingress_block ends up failing, we took the tcx_miniq_inc reference count on the ingress side, but not yet on the egress side. clsact_destroy() tests whether the {ingress,egress}_entry was non-NULL. However, even in midway failure on the replacement, both are in fact non-NULL with a valid egress_entry from the previous clsact instance. What we really need to test for is whether the qdisc instance-specific ingress or egress side previously got initialized. This adds a small helper for checking the miniq initialization called mini_qdisc_pair_inited, and utilizes that upon clsact_destroy() in order to fix the use-after-free scenario. Convert the ingress_destroy() side as well so both are consistent to each other.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于clsact qdisc初始化销毁不对称，可能导致释放后重用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 230bb13650b0f186f540500fd5f5f7096a822a2a ~ a73d95b57bf9faebdfed591bcb7ed9292062a84c -
Linux Linux 6.10 -

II. Public POCs for CVE-2026-23413

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III. Intelligence Information for CVE-2026-23413

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Same Patch Batch · Linux · 2026-04-02 · 6 CVEs total

CVE-2026-23415 7.8 HIGH futex: Fix UaF between futex_key_to_node_opt() and vma_replace_policy()
CVE-2026-23412 7.8 HIGH netfilter: bpf: defer hook memory release until rcu readers are done
CVE-2026-23414 7.5 HIGH tls: Purge async_hold in tls_decrypt_async_wait()
CVE-2026-23417 bpf: Fix constant blinding for PROBE_MEM32 stores
CVE-2026-23416 mm/mseal: update VMA end correctly on merge

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23413

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