CVE-2021-38545

CVE-2021-38545 is a medium-severity vulnerability in Raspberrypi Raspberry Pi 4 Model B Firmware with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

Raspberry Pi 3 B+ and 4 B devices through 2021-08-09, in certain specific use cases in which the device supplies power to audio-output equipment, allow remote attackers to recover speech signals from an LED on the device, via a telescope and an electro-optical sensor, aka a "Glowworm" attack. We assume that the Raspberry Pi supplies power to some speakers. The power indicator LED of the Raspberry Pi is connected directly to the power line, as a result, the intensity of a device's power indicator LED is correlative to the power consumption. The sound played by the speakers affects the Raspberry Pi's power consumption and as a result is also correlative to the light intensity of the LED. By analyzing measurements obtained from an electro-optical sensor directed at the power indicator LED of the Raspberry Pi, we can recover the sound played by the speakers.

Frequently asked questions

What is CVE-2021-38545?
Raspberry Pi 3 B+ and 4 B devices through 2021-08-09, in certain specific use cases in which the device supplies power to audio-output equipment, allow remote attackers to recover speech signals from an LED on the device, via a telescope and an electro-optical sensor, aka a "Glowworm" attack. We assume that the Raspberry Pi supplies power to some speakers. The power indicator LED of the Raspberry Pi is connected directly to the power line, as a result, the intensity of a device's power indicator LED is correlative to the power consumption. The sound played by the speakers affects the Raspberry Pi's power consumption and as a result is also correlative to the light intensity of the LED. By analyzing measurements obtained from an electro-optical sensor directed at the power indicator LED of the Raspberry Pi, we can recover the sound played by the speakers.
How severe is CVE-2021-38545?
CVE-2021-38545 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-38545 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-38545?
CVE-2021-38545 primarily affects Raspberrypi Raspberry Pi 4 Model B Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-38545?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-38545 published?
CVE-2021-38545 was published on 2021-08-11 and last updated on 2026-06-17.

References

Affected products (2)