CVE-2021-31615

Unencrypted Bluetooth Low Energy baseband links in Bluetooth Core Specifications 4.0 through 5.2 may permit an adjacent device to inject a crafted packet during the receive window of the listening device before the transmitting device initiates its packet transmission to achieve full MITM status without terminating the link. When applied against devices establishing or using encrypted links, crafted packets may be used to terminate an existing link, but will not compromise the confidentiality or integrity of the link.

Published: 2021-06-25 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31615 is rated Low Risk (32.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.40%). 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-2021-31615

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 0.25% 0.40% +0.16%
2 2026-05-10 0.14% 0.25% +0.11%
3 2026-02-05 — 0.14% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31615

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/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: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: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.
 1.6 3.6 [email protected]
2.9 2.0 LOW
AV:A/AC:M/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:M)
Exploitation needs some favorable conditions, but not exceptional ones.
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.
 5.5 2.9 [email protected]

Weakness enumeration for CVE-2021-31615

OS Trackers for CVE-2021-31615

vendor priority summary link
redhat medium — https://access.redhat.com/security/cve/CVE-2021-31615
suse medium CVE-2021-31615 severity moderate: SUSE including 5 source package names (bluez, bluez-cups, bluez-deprecated, bluez-devel, libbluetooth3), 82 product×package rows across 40 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 6, … (40 product lines)): Will Not Fix 82. https://www.suse.com/security/cve/CVE-2021-31615/
ubuntu medium CVE-2021-31615 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-2021-31615

Affected software / configurations for CVE-2021-31615

Vendor Product Version Raw CPE
bluetooth bluetooth_core_specification >= 4.0, <= 5.2 cpe:2.3:a:bluetooth:bluetooth_core_specification:*:*:*:*:*:*:*:*

References for CVE-2021-31615

cvelogic Threat Intelligence