What’s Vulnerable › Vulnerabilities

CVE-2020-15917

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-07-23 · updated 2026-06-17

Description

common/session.c in Claws Mail before 3.17.6 has a protocol violation because suffix data after STARTTLS is mishandled.

Affected products

• Claws-Mail: before 3.17.6 — fixed in 3.17.6
• Fedoraproject Fedora: 31, 32
• openSUSE Backports Sle: 15.0-sp1, 15.0-sp2
• openSUSE Leap: 15.1, 15.2

How to fix

Upgrade to a fixed version: Claws-Mail 3.17.6. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00090.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00002.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00060.html
• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00051.html
• http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00013.html
• https://git.claws-mail.org/?p=claws.git%3Ba=blob%3Bf=RELEASE_NOTES
• https://git.claws-mail.org/?p=claws.git%3Ba=commit%3Bh=fcc25329049b6f9bd8d890f1197ed61eb12e14d5
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6YVQB7NRBHO67Q74RS7RZCMW4ENRVBB4/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G7UX65342HRVDQML4G4GEVEUB764EUM5/
• https://security.gentoo.org/glsa/202007-56
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00090.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00002.html

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