VulnerabilityPublished 6 May 2026Updated 30 Oct 2026

CVE-2026-43167: Linux kernel · xfrm: always flush state and policy upon NETDEV_UNREGISTER event

Affects Linux kernelSource CVE Database V5

Compare

Not known to be exploited · fixed in d4df5a7da376e35089b8b601a86ff8a4cf997e2f : update Linux kernel when convenient.

Data as of 30 Oct 2026, 12:49 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Patch: Available – fixed in d4df5a7da376e35089b8b601a86ff8a4cf997e2f, a3c8fede034fa27892f87c863cbd5493167d17ed, 59581778792cbaf8ad788f4a21dc663ce986050e +3

Exploitation evidence

Disclosed: evidence found.
CVE published 6 May 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 ≥ d77e38e612a017480157fe6d2c1422f42cb5b7e3, < d4df5a7da376e35089b8b601a86ff8a4cf997e2f	Fixed in d4df5a7da376e35089b8b601a86ff8a4cf997e2f
LinuxLinux	Affected ≥ d77e38e612a017480157fe6d2c1422f42cb5b7e3, < a3c8fede034fa27892f87c863cbd5493167d17ed	Fixed in a3c8fede034fa27892f87c863cbd5493167d17ed
LinuxLinux	Affected ≥ d77e38e612a017480157fe6d2c1422f42cb5b7e3, < 59581778792cbaf8ad788f4a21dc663ce986050e	Fixed in 59581778792cbaf8ad788f4a21dc663ce986050e
LinuxLinux	Affected ≥ d77e38e612a017480157fe6d2c1422f42cb5b7e3, < 166801e49a5b5fc127b8c9e2f110f303cfddfbc3	Fixed in 166801e49a5b5fc127b8c9e2f110f303cfddfbc3
LinuxLinux	Affected ≥ d77e38e612a017480157fe6d2c1422f42cb5b7e3, < 8c75c455ecd3bfd2f36abf66edb7021c4fa19ec4	Fixed in 8c75c455ecd3bfd2f36abf66edb7021c4fa19ec4
LinuxLinux	Affected ≥ d77e38e612a017480157fe6d2c1422f42cb5b7e3, < 4efa91a28576054aae0e6dad9cba8fed8293aef8	Fixed in 4efa91a28576054aae0e6dad9cba8fed8293aef8

AI-suggested

A fix is available and has been applied in the Linux kernel commits identified by hashes d4df5a7da376e35089b8b601a86ff8a4cf997e2f, a3c8fede034fa27892f87c863cbd5493167d17ed, 59581778792cbaf8ad788f4a21dc663ce986050e, 166801e49a5b5fc127b8c9e2f110f303cfddfbc3, 8c75c455ecd3bfd2f36abf66edb7021c4fa19ec4, and 4efa91a28576054aae0e6dad9cba8fed8293aef8. Users should update to a fixed kernel version to remediate this issue.

Description

A reference count leak in the Linux kernel's xfrm subsystem was identified and fixed. The issue occurs because the xfrm_dev_unregister() function was implemented as a no-op, failing to release a reference to a network device acquired during xfrm state construction. This leads to a resource leak when the NETDEV_UNREGISTER event is processed. The fix reintroduces proper cleanup by flushing state and policy unconditionally upon device unregistration.

Impact

The vulnerability causes a reference count leak on network device structures in the kernel, which can lead to resource exhaustion or delays in device unregistration. This may impact system stability or network device management but does not directly indicate privilege escalation or code execution. No known exploits in the wild have been reported.

Summary

CVE-2026-43167 addresses a resource leak in the Linux kernel's xfrm subsystem related to IPsec hardware offloading. The vulnerability arises because the xfrm_dev_unregister() function was effectively disabled, causing references to 'struct net_device' acquired by xfrm_dev_state_add() during xfrm_state_construct() to never be released. This leak occurs during the NETDEV_UNREGISTER event, as the previous assumption that NETDEV_DOWN would always precede it and that the NETIF_F_HW_ESP feature bit would remain set was incorrect. The fix reintroduces xfrm_dev_unregister() to flush state and policy, releasing the held references and preventing the leak.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 12:48 UTC

Technical details

References

Community reviews

Related threats