CVE-2020-26556 [High] | Security Vulnerability in Bluetooth Core Specification

Mesh Provisioning in the Bluetooth Mesh profile 1.0 and 1.0.1 may permit a nearby device, able to conduct a successful brute-force attack on an insufficiently random AuthValue before the provisioning procedure times out, to complete authentication by leveraging Malleable Commitment.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-02-11	1.18%	0.90%	-0.27%
2	2025-11-21	0.17%	1.18%	+1.00%
3	2025-11-18	—	0.17%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-02-11

1.18%

0.90%

-0.27%

2025-11-21

0.17%

1.18%

+1.00%

2025-11-18

—

0.17%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.1	HIGH	`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.6	5.9	[email protected]
2.9	2.0	LOW	`AV:A/AC:M/Au:N/C:P/I:N/A:N` Click to expand Access vector (AV:A) Requires access to an adjacent network segment. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:N) No availability impact.	5.5	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.5

3.1

HIGH

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.6

5.9

[email protected]

2.9

2.0

LOW

AV:A/AC:M/Au:N/C:P/I:N/A:N Click to expand

Access vector (AV:A): Requires access to an adjacent network segment.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:N): No availability impact.

5.5

2.9

[email protected]

OS Trackers for CVE-2020-26556

vendor	priority	summary	link
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2020-26556
`suse`	medium	CVE-2020-26556 severity moderate: SUSE including 20 source package names (bluez, bluez-cups, …), 421 product×package rows across 71 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 7, … (71 product lines)): Known Not Affected 421.	https://www.suse.com/security/cve/CVE-2020-26556/
`ubuntu`	medium	CVE-2020-26556 medium priority: Ubuntu including 167 source packages (linux, linux-allwinner, …), 2145 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1677, ignored 307, needs-triage 161.	https://ubuntu.com/security/CVE-2020-26556

Affected software / configurations for CVE-2020-26556

Vendor	Product	Version	Raw CPE
bluetooth	bluetooth_core_specification	>= 1.0b, <= 5.2	cpe:2.3:a:bluetooth:bluetooth_core_specification::::::::
bluetooth	mesh_profile	1.0.0	cpe:2.3:a:bluetooth:mesh_profile:1.0.0:::::::*
bluetooth	mesh_profile	1.0.1	cpe:2.3:a:bluetooth:mesh_profile:1.0.1:::::::*

References for CVE-2020-26556

URL	Tags
https://kb.cert.org/vuls/id/799380	Third Party Advisory US Government Resource
https://www.bluetooth.com/learn-about-bluetooth/key-attributes/bluetooth-security/reporting-security/	Vendor Advisory
https://www.kb.cert.org/vuls/id/799380	Third Party Advisory US Government Resource

URL

CVE-2020-26556

Exploit prediction scoring system (EPSS) score for CVE-2020-26556

Common vulnerability scoring system (CVSS) metrics for CVE-2020-26556

Weakness enumeration for CVE-2020-26556

OS Trackers for CVE-2020-26556

Affected software / configurations for CVE-2020-26556

References for CVE-2020-26556