VulnerabilityPublished 26 Aug 2026Updated 30 Oct 2026

CVE-2026-74740: Linux kernel · net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f60b396ee174206fe08ebf997d16cd3801b77b22 : update Linux kernel when convenient.

Data as of 30 Oct 2026, 13:18 UTC

Severity

Medium

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

Thin evidence

One scorer or none

Patch: Available – fixed in f60b396ee174206fe08ebf997d16cd3801b77b22, abceabc4408fca6a9dd52611f5d197dec9390d63, 91d55fd1fdb85c8371ca8793c788ea7d5192383a +3

Exploitation evidence

Disclosed: evidence found.
CVE published 26 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 30 Oct 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 ≥ ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5, < f60b396ee174206fe08ebf997d16cd3801b77b22	Fixed in f60b396ee174206fe08ebf997d16cd3801b77b22
LinuxLinux	Affected ≥ ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5, < abceabc4408fca6a9dd52611f5d197dec9390d63	Fixed in abceabc4408fca6a9dd52611f5d197dec9390d63
LinuxLinux	Affected ≥ ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5, < 91d55fd1fdb85c8371ca8793c788ea7d5192383a	Fixed in 91d55fd1fdb85c8371ca8793c788ea7d5192383a
LinuxLinux	Affected ≥ ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5, < 28aa0c9dd0b1b38436995d4c15621ad3f896c7e3	Fixed in 28aa0c9dd0b1b38436995d4c15621ad3f896c7e3
LinuxLinux	Affected ≥ ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5, < 6b70886ebc428eed43a069c8944a931b5fb3f4e4	Fixed in 6b70886ebc428eed43a069c8944a931b5fb3f4e4
LinuxLinux	Affected ≥ ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5, < 1ec48b6715c29b20105e3485206602cff6c51ae5	Fixed in 1ec48b6715c29b20105e3485206602cff6c51ae5

AI-suggested

A fix is available and has been applied in specific commits identified by their hashes. Users should update their Linux kernel to a version that includes these fixes to remediate the vulnerability.

Description

A time-of-check to time-of-use (TOCTOU) race condition in the Linux kernel's net/sched subsystem could lead to a NULL pointer dereference when handling TC_ACT_GOTO_CHAIN actions. This occurs because the code performs two separate reads of a pointer that can be concurrently cleared, resulting in a NULL dereference. The issue has been fixed by consolidating the pointer read and check into a single atomic operation.

Impact

The vulnerability can cause a NULL pointer dereference in kernel code, which may lead to a kernel crash (panic) or denial of service. There is no indication of code execution or privilege escalation from the provided data.

Summary

CVE-2026-74740 addresses a TOCTOU vulnerability in the Linux kernel's net/sched act_api component. The function tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking the pointer a->goto_chain and then calling tcf_action_goto_chain_exec(), which dereferences this pointer again. A concurrent modification via tcf_action_set_ctrlact() can clear a->goto_chain between these two reads, causing a NULL pointer dereference in tcf_action_goto_chain_exec(). The fix involves performing a single rcu_dereference_bh() read of a->goto_chain, checking it once for NULL, and passing the pointer safely to tcf_action_goto_chain_exec(), eliminating the race condition.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 13:18 UTC

Technical details

References

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