CVE-2021-31855: KDE Messagelib through 5.17.0 reveals cleartext of encrypted messages in some situations. Deleting an attachment of a decrypted encrypted message stor...

Description

KDE Messagelib through 5.17.0 reveals cleartext of encrypted messages in some situations. Deleting an attachment of a decrypted encrypted message stored on a remote server (e.g., an IMAP server) causes KMail to upload the decrypted content of the message to the remote server. With a crafted message, a user could be tricked into decrypting an encrypted message and then deleting an attachment attached to this message. If the attacker has access to the messages stored on the email server, then the attacker could read the decrypted content of the encrypted message. This occurs in ViewerPrivate::deleteAttachment in messageviewer/src/viewer/viewer_p.cpp.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

0.60%

44.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-312

Affected Software

Vendor	Product	Versions
Kde	Messagelib	<= 5.17.0

References

Timeline

Published: Jun 2, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31855?

KDE Messagelib through 5.17.0 reveals cleartext of encrypted messages in some situations. Deleting an attachment of a decrypted encrypted message stored on a remote server (e.g., an IMAP server) causes KMail to upload the decrypted content of the message to the remote server. With a crafted message, a user could be tricked into decrypting an encrypted message and then deleting an attachment attached to this message. If the attacker has access to the messages stored on the email server, then the attacker could read the decrypted content of the encrypted message. This occurs in ViewerPrivate::deleteAttachment in messageviewer/src/viewer/viewer_p.cpp.

How severe is CVE-2021-31855?

CVE-2021-31855 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.60% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31855?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.