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CVE-2021-28139

27
FAUCET Score

CVE-2021-28139 is a critical vulnerability affecting the Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier, specifically impacting ESP32 devices. An attacker within radio range can exploit a flaw in how the system handles LMP Feature Response Extended packets, using a crafted Extended Features bitfield payload to achieve arbitrary code execution. This vulnerability carries a high CVSS score of 8.8, indicating a severe risk with low attack complexity and no user interaction required, potentially leading to complete compromise of confidentiality, integrity, and availability. While there is no evidence of active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered significant community discussion and media coverage, suggesting awareness within the security community.

Impacted Technologies

VendorProductVersion(s)CPE
<= 4.4CPE matchmatch criteria
cpe:2.3:a:espressif:esp-idf:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.39%
Probability of exploitation in next 30 days
EPSS Percentile
69.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0139 is in the 83rd percentile among its peer group of 1,875 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.2 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

dl.packetstormsecurity.net / papers/general/braktooth.pdf
Technical DescriptionThird Party Advisory
github.com / espressif/esp32-bt-lib
ProductThird Party Advisory
github.com / espressif/esp-idf
ProductThird Party Advisory
espressif.com / en/products/socs/esp32
ProductVendor Advisory