CVE-2021-46853: Alpine before 2.25 allows remote attackers to cause a denial of service (application crash) when LIST or LSUB

Q: How do I fix CVE-2021-46853?

alpine: upgrade to 2.25. Exact commands for each OS are on this page.

Q: Is CVE-2021-46853 being exploited?

CVE-2021-46853 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-46853 affect?

CVE-2021-46853 affects alpine. Severity is medium (CVSS 5.9). Alpine before 2.25 allows remote attackers to cause a denial of service (application crash) when LIST or LSUB is sent before STARTTLS.

Q: How urgent is CVE-2021-46853?

Priority 41/100. Remotely exploitable, no login, no user action

This month

MEDIUM 5.9REMOTEUPGRADE

CVE-2021-46853 is a medium-severity flaw (CVSS 5.9) affecting alpine. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-367
Published	2022-11-03
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: alpine project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-11-03 06:15 UTCPublished CVE record published
2026-06-17 04:15 UTCUpdated Record last modified

alpine project alpine UPGRADE

Affected: < 2.25

Fixed in: 2.25

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy alpine || rpm -q alpine || alpine --version

2. UPGRADE to 2.25 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade alpine

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade alpine

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-46853?

alpine: upgrade to 2.25. Exact commands for each OS are on this page.

Is CVE-2021-46853 being exploited?

CVE-2021-46853 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-46853 affect?

CVE-2021-46853 affects alpine. Severity is medium (CVSS 5.9). Alpine before 2.25 allows remote attackers to cause a denial of service (application crash) when LIST or LSUB is sent before STARTTLS.

How urgent is CVE-2021-46853?

Priority 41/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-23554 MEDIUM 6.5 UPGRADE Alpine is a scaffolding library in Java
CVE-2022-23553 HIGH 7.5 UPGRADE Alpine is a scaffolding library in Java
CVE-2021-38370 MEDIUM 5.9 UPGRADE In Alpine before 2.25, untagged responses from an IMAP server are accepted before STARTTLS.

References

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