How severe is CVE-2021-28136?

CVE-2021-28136 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-2021-28136 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28136?

CVE-2021-28136 affects Espressif Esp-idf. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-28136?

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

When was CVE-2021-28136 published?

CVE-2021-28136 was published on 2021-09-07 and last updated on 2026-06-17.

CVE-2021-28136

CVE-2021-28136 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. The underlying weakness is classified as CWE-787.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 3.3
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
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 multiple LMP IO Capability Request packets during the pairing process, allowing attackers in radio range to trigger memory corruption (and consequently a crash) in ESP32 via a replayed (duplicated) LMP packet.

Frequently asked questions

What is CVE-2021-28136?: The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly handle the reception of multiple LMP IO Capability Request packets during the pairing process, allowing attackers in radio range to trigger memory corruption (and consequently a crash) in ESP32 via a replayed (duplicated) LMP packet.
How severe is CVE-2021-28136?: CVE-2021-28136 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-2021-28136 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28136?: CVE-2021-28136 affects Espressif Esp-idf. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-28136?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-28136 published?: CVE-2021-28136 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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