CVE-2021-33038: An issue was discovered in management/commands/hyperkitty_import.py in HyperKitty through 1.3.4

Q: How do I fix CVE-2021-33038?

hyperkitty: upgrade to newer than 1.3.4; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-33038 being exploited?

CVE-2021-33038 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-2021-33038 affect?

CVE-2021-33038 affects hyperkitty, debian linux. Severity is high (CVSS 7.5). An issue was discovered in management/commands/hyperkitty_import.py in HyperKitty through 1.3.4. When importing a private mailing list's archives, these archives are publicly visible for the duration of the import. For example, sensitive in

Q: How urgent is CVE-2021-33038?

Priority 61/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2021-33038 is a high-severity flaw (CVSS 7.5) affecting hyperkitty, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in management/commands/hyperkitty_import.py in HyperKitty through 1.3.4. When importing a private mailing list's archives, these archives are publicly visible for the duration of the import. For example, sensitive information might be available on the web for an hour during a large migration from Mailman 2 to Mailman 3.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-276
Published	2021-05-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · hyperkitty project

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

Am I affected?

Timeline

2021-05-26 14:15 UTCPublished CVE record published
2026-06-17 03:54 UTCUpdated Record last modified

hyperkitty project hyperkitty UPGRADE

Affected: <= 1.3.4

Fixed in: newer than 1.3.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 1.3.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade hyperkitty

Note

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

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2021-33038?

hyperkitty: upgrade to newer than 1.3.4; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-33038 being exploited?

CVE-2021-33038 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-2021-33038 affect?

CVE-2021-33038 affects hyperkitty, debian linux. Severity is high (CVSS 7.5). An issue was discovered in management/commands/hyperkitty_import.py in HyperKitty through 1.3.4. When importing a private mailing list's archives, these archives are publicly visible for the duration of the import. For example, sensitive in

How urgent is CVE-2021-33038?

Priority 61/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

References

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