How severe is CVE-2021-28135?

CVE-2021-28135 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-28135 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28135?

CVE-2021-28135 affects Espressif Esp-idf. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-28135?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-28135 published?

CVE-2021-28135 was published on 2021-09-07 and last updated on 2026-06-17.

CVE-2021-28135

CVE-2021-28135 is a medium-severity vulnerability in Espressif Esp-idf with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 3.3
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Espressif Esp-idf
Published: 2021-09-07
Last modified: 2026-06-17

Description

The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly handle the reception of continuous unsolicited LMP responses, allowing attackers in radio range to trigger a denial of service (crash) in ESP32 by flooding the target device with LMP Feature Response data.

Frequently asked questions

What is CVE-2021-28135?: The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly handle the reception of continuous unsolicited LMP responses, allowing attackers in radio range to trigger a denial of service (crash) in ESP32 by flooding the target device with LMP Feature Response data.
How severe is CVE-2021-28135?: CVE-2021-28135 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-28135 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28135?: CVE-2021-28135 affects Espressif Esp-idf. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-28135?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-28135 published?: CVE-2021-28135 was published on 2021-09-07 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:espressif:esp-idf:*:*:*:*:*:*:*:*

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