VulnerabilityPublished 22 Aug 2026Updated 6 Nov 2026

CVE-2026-74620: Linux kernel · net/sched: act_gact, act_police: range check the fallback control action

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4 : patch Linux kernel soon.

Data as of 6 Nov 2026, 17:55 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch

Available – fixed in efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4, 5344e01179baa37547ab29fd7b8614f83faa190c, 883b56ae58fe657d8497806c7059646e9ba6dbd0 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 720f22fed81bc6fd1765db7014651b6718887bea, < efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4	Fixed in efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4
LinuxLinux	Affected ≥ 720f22fed81bc6fd1765db7014651b6718887bea, < 5344e01179baa37547ab29fd7b8614f83faa190c	Fixed in 5344e01179baa37547ab29fd7b8614f83faa190c
LinuxLinux	Affected ≥ 720f22fed81bc6fd1765db7014651b6718887bea, < 883b56ae58fe657d8497806c7059646e9ba6dbd0	Fixed in 883b56ae58fe657d8497806c7059646e9ba6dbd0
LinuxLinux	Affected ≥ 720f22fed81bc6fd1765db7014651b6718887bea, < 725efc2ab4a40affc4e285a2dc4896d103948a6c	Fixed in 725efc2ab4a40affc4e285a2dc4896d103948a6c
LinuxLinux	Affected ≥ 720f22fed81bc6fd1765db7014651b6718887bea, < 92f00f1d4d204a428b38e26fce3baee144b6955d	Fixed in 92f00f1d4d204a428b38e26fce3baee144b6955d
LinuxLinux	Affected ≥ 720f22fed81bc6fd1765db7014651b6718887bea, < 6bcb8839aa2d686964a4154650afc4db91e1c514	Fixed in 6bcb8839aa2d686964a4154650afc4db91e1c514

AI-suggested

A fix is available and has been applied in multiple Linux kernel commits. Systems running affected versions should update to a fixed kernel version that includes these patches. No additional mitigation is required beyond applying the official fix.

Description

A vulnerability in the Linux kernel's net/sched subsystem affects the act_gact and act_police modules. The issue arises because the fallback control action is not properly range-checked, allowing user space to specify a control action value (TC_ACT_CONSUMED) outside the expected range. This causes the kernel to leak one sk_buff and its data buffer per packet processed, leading to unbounded memory leaks on affected systems. The flaw has been fixed in multiple Linux kernel commits.

Impact

This vulnerability causes an unbounded memory leak in the Linux kernel's networking subsystem, specifically leaking one sk_buff and its data buffer per packet processed by the affected filters. This can lead to resource exhaustion on affected systems, potentially degrading system performance or causing instability over time. There is no indication of direct code execution or privilege escalation from the provided data.

Summary

The Linux kernel's net/sched subsystem contains a vulnerability where the fallback control action in act_gact and act_police is not properly range-checked. The function tcf_action_check_ctrlact() validates the primary control action but does not validate the secondary control actions TCA_GACT_PROB.paction and TCA_POLICE_RESULT, which can accept out-of-range values such as TC_ACT_CONSUMED. This verdict causes the kernel to skip freeing the associated sk_buff, resulting in a memory leak of one sk_buff plus its data buffer per packet traversing the filter. The vulnerability was introduced after the addition of TC_ACT_CONSUMED and was not accounted for in existing guards. The issue was reproduced on Linux kernel version 5.3 and fixed by applying proper range checks to the fallback control actions, rejecting invalid values with -EINVAL.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Nov 2026, 17:55 UTC

Technical details

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