CVE-2021-33038 Exposure of sensitive information to an unauthorized actor in HyperKitty

What is CVE-2021-33038?

CVE-2021-33038 is a high-severity vulnerability in Debian Debian Linux, published on 26 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-276

Which versions are affected by CVE-2021-33038?

3 open source packages ship an affected version, including hyperkitty and HyperKitty. It affects 2 products.

Products include Debian Debian Linux, Hyperkitty Project Hyperkitty.

How do I fix CVE-2021-33038?

Upgrade hyperkitty to 1.3.5 or later.

Is CVE-2021-33038 being exploited?

There is no known exploitation of CVE-2021-33038 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-33038, DSA-4922-1, GHSA-h39g-q63v-4h9p, PYSEC-2021-77, UBUNTU-CVE-2021-33038, openSUSE-SU-2021:0861-1.