CVE-2021-31611

The Bluetooth Classic implementation on Zhuhai Jieli AC690X and AC692X devices does not properly handle an out-of-order LMP Setup procedure that is followed by a malformed LMP packet, allowing attackers in radio range to deadlock a device via a crafted LMP packet. The user needs to manually reboot the device to restore communication.

Published: 2021-09-07 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31611 is rated Low Risk (32.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.35%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-31611

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.06% 0.35% +0.30%
2 2023-03-07 1.02% 0.06% -0.96%
3 2022-04-01 — 1.02% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31611

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.7 3.1 MEDIUM
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:N/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.1 3.6 [email protected]
3.3 2.0 LOW
AV:A/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:A)
Requires access to an adjacent network segment.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.5 2.9 [email protected]

Weakness enumeration for CVE-2021-31611

Affected software / configurations for CVE-2021-31611

Vendor Product Version Raw CPE
zh-jieli ac6901_firmware — cpe:2.3:o:zh-jieli:ac6901_firmware:-:*:*:*:*:*:*:*
zh-jieli ac6925_firmware — cpe:2.3:o:zh-jieli:ac6925_firmware:-:*:*:*:*:*:*:*
zh-jieli ac6926_firmware — cpe:2.3:o:zh-jieli:ac6926_firmware:-:*:*:*:*:*:*:*
zh-jieli ac6928_firmware — cpe:2.3:o:zh-jieli:ac6928_firmware:-:*:*:*:*:*:*:*
zh-jieli ac6921_firmware — cpe:2.3:o:zh-jieli:ac6921_firmware:-:*:*:*:*:*:*:*

References for CVE-2021-31611

cvelogic Threat Intelligence