CVE-2020-24661: GNOME Geary before 3.36.3 mishandles pinned TLS certificate verification for IMAP and SMTP services using inva

Q: How do I fix CVE-2020-24661?

geary: upgrade to 3.36.3; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2020-24661 being exploited?

CVE-2020-24661 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-2020-24661 affect?

CVE-2020-24661 affects geary, fedora. Severity is medium (CVSS 5.9). GNOME Geary before 3.36.3 mishandles pinned TLS certificate verification for IMAP and SMTP services using invalid TLS certificates (e.g., self-signed certificates) when the client system is not configured to use a system-provided PKCS#11 st

Q: How urgent is CVE-2020-24661?

Priority 46/100. Public exploit reference; Remotely exploitable, no login, no user action

This week

MEDIUM 5.9REMOTEUPGRADEMITIGATE

CVE-2020-24661 is a medium-severity flaw (CVSS 5.9) affecting geary, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

GNOME Geary before 3.36.3 mishandles pinned TLS certificate verification for IMAP and SMTP services using invalid TLS certificates (e.g., self-signed certificates) when the client system is not configured to use a system-provided PKCS#11 store. This allows a meddler in the middle to present a different invalid certificate to intercept incoming and outgoing mail.

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-295
Published	2020-08-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · gnome

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

Am I affected?

Timeline

2020-08-26 16:15 UTCPublished CVE record published
2026-06-17 03:05 UTCUpdated Record last modified

gnome geary UPGRADE

Affected: < 3.36.3

Fixed in: 3.36.3

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.36.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade geary

Note

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

fedoraproject fedora MITIGATE

Affected: 31 · 32

Fixed in: no fixed release known

Safe to downgrade to: a release before 31

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-2020-24661?

geary: upgrade to 3.36.3; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-24661 being exploited?

CVE-2020-24661 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-2020-24661 affect?

CVE-2020-24661 affects geary, fedora. Severity is medium (CVSS 5.9). GNOME Geary before 3.36.3 mishandles pinned TLS certificate verification for IMAP and SMTP services using invalid TLS certificates (e.g., self-signed certificates) when the client system is not configured to use a system-provided PKCS#11 st

How urgent is CVE-2020-24661?

Priority 46/100. Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2014-5444 MEDIUM 4.3 UPGRADE Geary before 0.6.3 does not present the user with a warning when a TLS certificate error is detected, which ma

References

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