CVE-2020-15954: KDE KMail 19.12.3 (aka 5.13.3) engages in unencrypted POP3 communication during times when the UI indicates th

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MEDIUM 6.5WATCHLISTDOWNGRADEMITIGATE

CVE-2020-15954 is a medium-severity flaw (CVSS 6.5) affecting kmail, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

KDE KMail 19.12.3 (aka 5.13.3) engages in unencrypted POP3 communication during times when the UI indicates that encryption is in use.

Why this priority

On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.7% (top 49%)
CISA exploited list	No
Weakness	CWE-319
Published	2020-07-27
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · kde

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

Am I affected?

Timeline

2020-07-27 07:15 UTCPublished CVE record published
2026-06-17 02:57 UTCUpdated Record last modified

kde kmail DOWNGRADE

Affected: 19.12.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 19.12.3

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 19.12.3 (Debian / Ubuntu)

apt-cache madison kmail sudo apt install kmail=<VERSION_BEFORE_19.12.3> sudo apt-mark hold kmail

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list kmail sudo dnf downgrade kmail-<VERSION_BEFORE_19.12.3> sudo dnf versionlock add kmail

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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-2020-15954?

kmail: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-15954 being exploited?

CVE-2020-15954 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-2020-15954 affect?

CVE-2020-15954 affects kmail, debian linux. Severity is medium (CVSS 6.5). KDE KMail 19.12.3 (aka 5.13.3) engages in unencrypted POP3 communication during times when the UI indicates that encryption is in use.

How urgent is CVE-2020-15954?

Priority 41/100. On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2021-38373 MEDIUM 5.3 DOWNGRADE In KDE KMail 19.12.3 (aka 5.13.3), the SMTP STARTTLS option is not honored (and cleartext messages are sent) u
CVE-2020-11880 MEDIUM 6.5 UPGRADE An issue was discovered in KDE KMail before 19.12.3
CVE-2019-10732 MEDIUM 4.3 DOWNGRADE MITIGATE In KDE KMail 5.2.3, an attacker in possession of S/MIME or PGP encrypted emails can wrap them as sub-parts wit
CVE-2017-9604 HIGH 7.5 UPGRADE UPGRADE KDE kmail before 5.5.2 and messagelib before 5.5.2, as distributed in KDE Applications before 17.04.2, do not
CVE-2016-7968 MEDIUM 6.5 UPGRADE KMail since version 5.3.0 used a QWebEngine based viewer that had JavaScript enabled

References

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