CVE-2021-34337

An issue was discovered in Mailman Core before 3.3.5. An attacker with access to the REST API could use timing attacks to determine the value of the configured REST API password and then make arbitrary REST API calls. The REST API is bound to localhost by default, limiting the ability for attackers to exploit this, but can optionally be made to listen on other interfaces.

Published: 2023-04-15 Last update: 2025-02-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-34337 is rated Low Risk (32.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.30%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2021-34337

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 0.17% 0.30% +0.13%
2 2026-04-19 0.42% 0.17% -0.25%
3 2026-04-13 — 0.42% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-34337

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.3 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.0 5.2 [email protected]
6.3 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.0 5.2 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2021-34337

GitHub Security Advisory for CVE-2021-34337

GHSA-2jg5-xgvv-4wq7 · Severity: high · Ecosystem: pip — Mailman Core vulnerable to timing attacks

OS Trackers for CVE-2021-34337

vendor priority summary link
debian not yet assigned CVE-2021-34337 not yet assigned priority: Debian including 1 source packages (mailman3), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2021-34337
redhat medium — https://access.redhat.com/security/cve/CVE-2021-34337
suse high CVE-2021-34337 severity important: SUSE including 3 source package names (mailman, mailman3-3.3.5-2.1, python3-mailman-3.3.5-1.1), 18 product×package rows across 17 product lines (HPE Helion OpenStack 8, SUSE Linux Enterprise High Performance Computing 12 SP5, … (17 product lines)): Known Not Affected 16, Fixed 2. https://www.suse.com/security/cve/CVE-2021-34337/
ubuntu medium CVE-2021-34337 medium priority: Ubuntu including 1 source packages (mailman3), 14 status rows across 14 suites (bionic, focal, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 6, ignored 3, DNE 2, needed 2, released 1. https://ubuntu.com/security/CVE-2021-34337

Affected software / configurations for CVE-2021-34337

Vendor Product Version Raw CPE
gnu mailman < 3.3.5 cpe:2.3:a:gnu:mailman:*:*:*:*:*:*:*:*

References for CVE-2021-34337

cvelogic Threat Intelligence