What is CVE-2016-20021?

CVE-2016-20021 is a critical-severity vulnerability in Gentoo Portage, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2024-01-12.

How severe is CVE-2016-20021?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2016-20021 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Gentoo Portage

CVE-2016-20021

In Gentoo Portage before 3.0.47, there is missing PGP validation of executed code: the standalone emerge-webrsync downloads a .gpgsig file but does not perform signature verification. Unless emerge-webrsync is used, Portage is not vulnerable.

Published 2024-01-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (38.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 38.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Gentoo Portage

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

wiki.gentoo.org/wiki/Portage (Product)
gitweb.gentoo.org/proj/portage.git/tree/NEWS (Release Notes)
bugs.gentoo.org/597800 (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2016-20021?: CVE-2016-20021 is a critical-severity vulnerability in Gentoo Portage, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2024-01-12.
How severe is CVE-2016-20021?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2016-20021 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.