CVE-2020-15917

Name: CVE-2020-15917
Creator: NVD / NIST
Published: 2020-07-23T19:15:10.137+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.59%

Last modified Jun 17, 2026

CVE-2020-15917 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. common/session.c in Claws Mail before 3.17.6 has a protocol violation because suffix data after STARTTLS is mishandled.. EPSS estimates a 2.59% chance of exploitation in the next 30 days.

Description

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

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

2.59%

83.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions	Update
Claws-Mail	Claws-Mail	< 3.17.6	—
Fedoraproject	Fedora	31	—
Fedoraproject	Fedora	32	—
Opensuse	Backports Sle	15.0	Sp1
Opensuse	Leap	15.1	—
Opensuse	Leap	15.2	—

References

http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00090.htmlMailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00002.htmlBroken Link, Mailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00060.htmlBroken Link, Mailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00051.htmlBroken Link, Mailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00013.htmlBroken Link, Mailing List, Third Party Advisory
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/202007-56Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00090.htmlMailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00002.htmlBroken Link, Mailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00060.htmlBroken Link, Mailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00051.htmlBroken Link, Mailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00013.htmlBroken Link, Mailing List, Third Party Advisory
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/202007-56Third Party Advisory

Timeline

Published: Jul 23, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15917?

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

How severe is CVE-2020-15917?

CVE-2020-15917 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.59% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15917?

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.

Are you affected by CVE-2020-15917?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST