CVE-2020-7694: This affects all versions of package uvicorn. The request logger provided by the package is vulnerable to ASNI escape sequence injection. Whenever any...

Description

This affects all versions of package uvicorn. The request logger provided by the package is vulnerable to ASNI escape sequence injection. Whenever any HTTP request is received, the default behaviour of uvicorn is to log its details to either the console or a log file. When attackers request crafted URLs with percent-encoded escape sequences, the logging component will log the URL after it's been processed with urllib.parse.unquote, therefore converting any percent-encoded characters into their single-character equivalent, which can have special meaning in terminal emulators. By requesting URLs with crafted paths, attackers can: * Pollute uvicorn's access logs, therefore jeopardising the integrity of such files. * Use ANSI sequence codes to attempt to interact with the terminal emulator that's displaying the logs (either in real time or from a file).

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.34%

67.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Encode	Uvicorn	All versions

References

https://github.com/encode/uvicornProduct, Third Party Advisory
https://snyk.io/vuln/SNYK-PYTHON-UVICORN-575560Exploit, Third Party Advisory
https://github.com/encode/uvicornProduct, Third Party Advisory
https://snyk.io/vuln/SNYK-PYTHON-UVICORN-575560Exploit, Third Party Advisory

Timeline

Published: Jul 27, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-7694?

This affects all versions of package uvicorn. The request logger provided by the package is vulnerable to ASNI escape sequence injection. Whenever any HTTP request is received, the default behaviour of uvicorn is to log its details to either the console or a log file. When attackers request crafted URLs with percent-encoded escape sequences, the logging component will log the URL after it's been processed with urllib.parse.unquote, therefore converting any percent-encoded characters into their single-character equivalent, which can have special meaning in terminal emulators. By requesting URLs with crafted paths, attackers can: * Pollute uvicorn's access logs, therefore jeopardising the integrity of such files. * Use ANSI sequence codes to attempt to interact with the terminal emulator that's displaying the logs (either in real time or from a file).

How severe is CVE-2020-7694?

CVE-2020-7694 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.34% probability of exploitation in the next 30 days.

How do I fix CVE-2020-7694?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.