Log injection in uvicorn

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2020-7694: 1.36% estimated exploitation activity in the next 30 days; percentile 71.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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).

Published by the source

29 Jul 2020, 18:07 UTC

Last modified by the source

18 Nov 2024, 22:34 UTC

Source last checked

26 Oct 2026, 13:27 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-33c7-2mpw-hg34

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-33c7-2mpw-hg34

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# Patch Next advisory brief: CVE-2020-7694

Advisory: Log injection in uvicorn
IDs: CVE-2020-7694, GHSA-33c7-2mpw-hg34
Record: https://patchnext.com/advisories/cve-2020-7694 (revision 3, source checked 26 Oct 2026, 13:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: uvicorn 0.11.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI uvicorn: affected < 0.11.7; fixed in 0.11.7

## Suggested inspection (read-only)
- `python -m pip show uvicorn`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on uvicorn.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-33c7-2mpw-hg34 (OSV record GHSA-33c7-2mpw-hg34 lists affected ranges: PyPI uvicorn >=0 <0.11.7 (fixed))
- Verified: https://github.com/advisories/GHSA-33c7-2mpw-hg34 (GitHub-reviewed advisory GHSA-33c7-2mpw-hg34 lists affected ranges: PyPI uvicorn >=0 <0.11.7)

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