What is CVE-2021-46853?

CVE-2021-46853 is a medium-severity vulnerability in Alpine Project, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 5.9/10. Published 2022-11-03.

How severe is CVE-2021-46853?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Alpine Project

CVE-2021-46853

Alpine before 2.25 allows remote attackers to cause a denial of service (application crash) when LIST or LSUB is sent before STARTTLS.

Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)

Published 2022-11-03 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.009 (58.6th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: +0.000

Affected products

Alpine Project

Weakness classification (CWE)

CWE-367 — Time-of-check Time-of-use (TOCTOU) Race Condition

References

nostarttls.secvuln.info/ (Technical Description, Third Party Advisory)
bugs.gentoo.org/807613 (Third Party Advisory, Issue Tracking)
security.gentoo.org/glsa/202301-07 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2021-46853?: CVE-2021-46853 is a medium-severity vulnerability in Alpine Project, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 5.9/10. Published 2022-11-03.
How severe is CVE-2021-46853?: Medium severity. CVSS v3 base score is 5.9 out of 10.