CVE-2020-15917

What it is

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

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

2.6% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2020-07-23 00:00 UTC ReservedThe CVE id was reserved by its CNA
2. 2020-07-23 19:15 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-06-17 02:57 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.6% in the next 30 days (EPSS).
• Severity: 9.8 CRITICAL (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2020-07-23 19:15 UTC

Last modified

2026-06-17 02:57 UTC

Exploit probability

2.6% · EPSS, next 30 days

Record status

Modified

Affected

• claws-mail < 3.17.6
• Fedoraproject Fedora 31
• Fedoraproject Fedora 32
• Opensuse Backports Sle 15.0
• Opensuse Leap 15.1
• Opensuse Leap 15.2

Attack profile CVSS 3.1 · 9.8

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-15917.md and follow it. Check whether this project is affected by CVE-2020-15917. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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