CVE-2021-38370: In Alpine before 2.25, untagged responses from an IMAP server are accepted before STARTTLS.

Q: How do I fix CVE-2021-38370?

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

Q: Is CVE-2021-38370 being exploited?

CVE-2021-38370 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-2021-38370 affect?

CVE-2021-38370 affects alpine. Severity is medium (CVSS 5.9). In Alpine before 2.25, untagged responses from an IMAP server are accepted before STARTTLS.

Q: How urgent is CVE-2021-38370?

Priority 49/100. Public exploit reference; Remotely exploitable, no login, no user action

This week

MEDIUM 5.9REMOTEUPGRADE

CVE-2021-38370 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.

In Alpine before 2.25, untagged responses from an IMAP server are accepted before STARTTLS.

Why this priority

Public exploit reference
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	1.6% (top 25%)
CISA exploited list	No
Weakness	CWE-77
Published	2021-08-10
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

2021-08-10 15:15 UTCPublished CVE record published
2026-06-17 04:01 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-2021-38370?

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

Is CVE-2021-38370 being exploited?

CVE-2021-38370 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-2021-38370 affect?

CVE-2021-38370 affects alpine. Severity is medium (CVSS 5.9). In Alpine before 2.25, untagged responses from an IMAP server are accepted before STARTTLS.

How urgent is CVE-2021-38370?

Priority 49/100. Public exploit reference; 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-2021-46853 MEDIUM 5.9 UPGRADE Alpine before 2.25 allows remote attackers to cause a denial of service (application crash) when LIST or LSUB
CVE-2020-14929 HIGH 7.5 UPGRADE MITIGATE Alpine before 2.23 silently proceeds to use an insecure connection after a /tls is sent in certain circumstanc

References

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