CVE-2020-15953

Name: CVE-2020-15953
Creator: NVD / NIST
Published: 2020-07-27T07:15:10.91+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.4/10EPSS 2.39%

Last modified Jun 17, 2026

CVE-2020-15953 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. LibEtPan through 1.9.4, as used in MailCore 2 through 0.6.3 and other products, has a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a "begin TLS" response, the client reads additional data (e.g., from a meddler-in-the-middle attacker) and evaluates it in a TLS context, aka "response injection.". EPSS estimates a 2.39% chance of exploitation in the next 30 days.

Description

LibEtPan through 1.9.4, as used in MailCore 2 through 0.6.3 and other products, has a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a "begin TLS" response, the client reads additional data (e.g., from a meddler-in-the-middle attacker) and evaluates it in a TLS context, aka "response injection."

Metrics

CVSS 3.1

7.4/10

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

EPSS Probability

2.39%

81.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-74

Affected Software

Vendor	Product	Versions
Libetpan Project	Libetpan	<= 1.9.4
Libmailcore	Mailcore2	<= 0.6.3
Fedoraproject	Fedora	31
Fedoraproject	Fedora	32
Debian	Debian Linux	9.0

References

http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00060.htmlBroken Link
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00075.htmlBroken Link
https://github.com/dinhvh/libetpan/issues/386Exploit, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/08/msg00026.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M65FVH5XPS23NLHFN3ABEGBSCHZAISXN/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QFBWNA5REI5ZGW2DAOEAVHM23MOU6O5J/
https://security.gentoo.org/glsa/202007-55Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00060.htmlBroken Link
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00075.htmlBroken Link
https://github.com/dinhvh/libetpan/issues/386Exploit, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/08/msg00026.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M65FVH5XPS23NLHFN3ABEGBSCHZAISXN/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QFBWNA5REI5ZGW2DAOEAVHM23MOU6O5J/
https://security.gentoo.org/glsa/202007-55Third Party Advisory

Timeline

Published: Jul 27, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15953?

How severe is CVE-2020-15953?

CVE-2020-15953 has a CVSS score of 7.4/10 (HIGH severity). The EPSS model estimates a 2.39% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15953?

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-2020-15953?

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

Scan your code now

Source: NVD / NIST