CVE-2020-12137

GNU Mailman 2.x before 2.1.30 uses the .obj extension for scrubbed application/octet-stream MIME parts. This behavior may contribute to XSS attacks against list-archive visitors, because an HTTP reply from an archive web server may lack a MIME type, and a web browser may perform MIME sniffing, conclude that the MIME type should have been text/html, and execute JavaScript code.

Published: 2020-04-24 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-12137 is rated Moderate Risk (49.9/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.31%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-12137

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 5.22% 2.31% -2.91%
2 2026-01-16 3.67% 5.22% +1.54%
3 2025-12-28 — 3.67% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-12137

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2020-12137

OS Trackers for CVE-2020-12137

vendor priority summary link
redhat medium — https://access.redhat.com/security/cve/CVE-2020-12137
suse medium — https://www.suse.com/security/cve/CVE-2020-12137/
ubuntu medium CVE-2020-12137 medium priority: Ubuntu including 1 source packages (mailman), 10 status rows across 10 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): DNE 5, released 3, ignored 1, needs-triage 1. https://ubuntu.com/security/CVE-2020-12137

Affected software / configurations for CVE-2020-12137

Vendor Product Version Raw CPE
gnu mailman >= 2.0, < 2.1.30 cpe:2.3:a:gnu:mailman:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
fedoraproject fedora 31 cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
opensuse backports_sle 15.0 cpe:2.3:a:opensuse:backports_sle:15.0:sp2:*:*:*:*:*:*
opensuse leap 15.2 cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*

References for CVE-2020-12137

URL Tags
http://bazaar.launchpad.net/~mailman-coders/mailman/2.1/view/head:/NEWS Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00047.html Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00063.html Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/04/24/3 Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00002.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6YCMGTTOXXCVM4O6CYZLTZDX6YLYORNF/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G4COSBBEMJYLV7WSW5QTUJUOFJFK47KK/
https://usn.ubuntu.com/4348-1/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4664 Third Party Advisory
https://www.openwall.com/lists/oss-security/2020/02/24/2 Mailing List Third Party Advisory
https://www.openwall.com/lists/oss-security/2020/02/24/3 Mailing List Third Party Advisory
cvelogic Threat Intelligence