VulnerabilityPublished 1 May 2026Updated 6 Nov 2026

CVE-2026-43020: Linux kernel · Bluetooth: MGMT: validate LTK enc_size on load

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f71695e81f4cb428f3c7e2138eae88199005b52c : patch Linux kernel soon.

Data as of 6 Nov 2026, 16:33 UTC

Severity

High

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

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 f71695e81f4cb428f3c7e2138eae88199005b52c, c34577f517b556fb6ca173d45bf7e766ae2564ce, b8dbe9648d69059cfe3a28917bfbf7e61efd7f15 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 1 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 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 ≥ 346af67b8d116f01ef696fd47959a55deb2db8b6, < f71695e81f4cb428f3c7e2138eae88199005b52c	Fixed in f71695e81f4cb428f3c7e2138eae88199005b52c
LinuxLinux	Affected ≥ 346af67b8d116f01ef696fd47959a55deb2db8b6, < c34577f517b556fb6ca173d45bf7e766ae2564ce	Fixed in c34577f517b556fb6ca173d45bf7e766ae2564ce
LinuxLinux	Affected ≥ 346af67b8d116f01ef696fd47959a55deb2db8b6, < b8dbe9648d69059cfe3a28917bfbf7e61efd7f15	Fixed in b8dbe9648d69059cfe3a28917bfbf7e61efd7f15
LinuxLinux	Affected ≥ 346af67b8d116f01ef696fd47959a55deb2db8b6, < 257cdb960d8ff6d60bb6461b03c814b6cf0c9e64	Fixed in 257cdb960d8ff6d60bb6461b03c814b6cf0c9e64
LinuxLinux	Affected ≥ 346af67b8d116f01ef696fd47959a55deb2db8b6, < 82f342b3b006ca1d65f4890c05f2ec32fcb808b6	Fixed in 82f342b3b006ca1d65f4890c05f2ec32fcb808b6
LinuxLinux	Affected ≥ 346af67b8d116f01ef696fd47959a55deb2db8b6, < 50fb64defa72a3fecd0af1ca7c6b47b5c5c2b257	Fixed in 50fb64defa72a3fecd0af1ca7c6b47b5c5c2b257

AI-suggested

The vulnerability has been fixed in the Linux kernel with multiple commits. Users and administrators should update to the fixed kernel versions containing these commits to mitigate the issue. No additional mitigation actions are required beyond applying the official fix.

Description

A vulnerability in the Linux kernel Bluetooth management subsystem allows an oversized encryption size (enc_size) value in Long Term Keys (LTK) to overflow a fixed-size stack buffer. This occurs because the user-provided enc_size is used without proper validation, potentially leading to a stack buffer overflow when replying to LE LTK requests. The issue has been resolved by rejecting oversized enc_size values during validation to prevent invalid keys from being stored.

Impact

An attacker could exploit this vulnerability by providing an oversized enc_size value in a Bluetooth LTK, causing a stack buffer overflow in the kernel. This could potentially lead to memory corruption and impact system stability or security. However, there is no evidence of known exploits in the wild at this time.

Summary

CVE-2026-43020 addresses a vulnerability in the Linux kernel's Bluetooth MGMT component where the enc_size field of Long Term Keys (LTK) is not properly validated on load. The enc_size value, if larger than the 16-byte key buffer, can cause a stack buffer overflow during LE LTK reply operations. The fix involves validating and rejecting enc_size values that exceed the buffer size, ensuring invalid keys do not reach the stored key state. The vulnerability affects Linux kernel version 3.4 and has been fixed in multiple commits identified by their hashes.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Nov 2026, 16:33 UTC

Technical details

References

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