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CVE-2021-31855

KDE Messagelib through 5.17.0 reveals cleartext of encrypted messages in some situations....

6.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.61%Up 0.2 points since Jun 3, 2021
90%50%10%1%

What each source reports

NVD Score used 6.5

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.

Record
CVE-2021-31855
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS 2.0
4.0 MediumAV:N/AC:L/Au:S/C:P/I:N/A:N
Weakness
CWE-312
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2021-31855
Updated
2026-11-02
EUVDEUVD-2021-18730 No score

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.

Record
EUVD-2021-18730
Updated
2026-11-03
GitHub AdvisoriesGHSA-h76g-vp43-8cw5 6.5

KDE Messagelib through 5.17.0 reveals cleartext of encrypted messages in some situations....

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.

Record
GHSA-h76g-vp43-8cw5
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-312, CWE-319
Updated
2026-11-02
OSV 6.5

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.

Record
CVE-2021-31855
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2021-31855 6.5

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.

Record
DEBIAN-CVE-2021-31855
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2021-31855 6.5

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.

Record
UBUNTU-CVE-2021-31855
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVMGASA-2021-0208 No score

Updated messagelib packages fix security vulnerability

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. This is not easily noticeable by the user because KMail does not display the decrypted content.

With a specially 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 (CVE-2021-31855).

Record
MGASA-2021-0208
Updated
2026-11-02
OSVopenSUSE-SU-2024:11046-1 No score

messagelib-21.08.1-1.2 on GA media

These are all security issues fixed in the messagelib-21.08.1-1.2 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:11046-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
kf5-messagelib
Debian:12
before 4:20.08.3-5
4:20.08.3-5
messagelib
Mageia:7
before 19.04.0-1.2.mga7
19.04.0-1.2.mga7
messagelib
Mageia:8
before 20.12.0-1.1.mga8
20.12.0-1.1.mga8
kdepim4
Ubuntu:18.04:LTS
All versions, plus listed versions
4:4.14.10-7
None known
kf5-messagelib
Ubuntu:Pro:18.04:LTS
All versions, plus listed versions
4:17.04.3-0ubuntu14:17.04.3-0ubuntu24:17.08.3-0ubuntu14:17.08.3-0ubuntu24:17.12.2-0ubuntu34:17.12.3-0ubuntu24:17.12.3-0ubuntu34:17.12.3-0ubuntu3+esm1
None known
kf5-messagelib
Ubuntu:20.04:LTS
All versions, plus listed versions
4:19.04.3-0ubuntu14:19.04.3-0ubuntu24:19.12.3-0ubuntu1
None known
kf5-messagelib
Ubuntu:22.04:LTS
All versions, plus listed versions
4:21.08.1-0ubuntu14:21.08.3-0ubuntu24:21.11.80-0ubuntu14:21.11.90-0ubuntu14:21.12.0-0ubuntu14:21.12.1-0ubuntu14:21.12.2-0ubuntu14:21.12.3-0ubuntu1
None known
kf5-messagelib
Ubuntu:24.04:LTS
All versions, plus listed versions
4:23.08.1-0ubuntu14:23.08.2-0ubuntu14:23.08.3-0ubuntu14:23.08.4-0ubuntu14:23.08.5-0ubuntu14:23.08.5-0ubuntu34:23.08.5-0ubuntu4
None known
messagelib
openSUSE:Tumbleweed
From an advisory covering 2 CVEs
before 21.08.1-1.2
21.08.1-1.2

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-31855 is a medium vulnerability (CVSS 6.5) in Kde Messagelib, published May 7, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.61%, the 49th percentile. Fixed in kf5-messagelib 4:20.08.3-5.

References

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