CVE-2021-46853

Alpine before 2.25 allows remote attackers to cause a denial of service (application crash) when LIST or LSUB is sent before STARTTLS.

Published: 2022-11-03 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-46853 is rated Moderate Risk (42.6/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.84%). 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-2021-46853

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 0.41% 0.84% +0.43%
2 2026-04-28 0.32% 0.41% +0.09%
3 2026-02-11 — 0.32% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-46853

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2021-46853

OS Trackers for CVE-2021-46853

vendor priority summary link
alpine — CVE-2021-46853: 1 source package rows (alpine); 2 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 2. https://security.alpinelinux.org/vuln/CVE-2021-46853
debian not yet assigned CVE-2021-46853 not yet assigned priority: Debian including 1 source packages (alpine), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2021-46853
gentoo low CVE-2021-46853: 1 GLSA(s) (202301-07), 1 atom(s) (mail-client/alpine); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-46853
ubuntu medium CVE-2021-46853 medium priority: Ubuntu including 1 source packages (alpine), 12 status rows across 12 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): not-affected 7, released 4, ignored 1. https://ubuntu.com/security/CVE-2021-46853

Affected software / configurations for CVE-2021-46853

Vendor Product Version Raw CPE
alpine_project alpine < 2.25 cpe:2.3:a:alpine_project:alpine:*:*:*:*:*:*:*:*

References for CVE-2021-46853

URL Tags
https://bugs.gentoo.org/807613 Issue Tracking Third Party Advisory
https://nostarttls.secvuln.info/ Technical Description Third Party Advisory
https://security.gentoo.org/glsa/202301-07 Third Party Advisory
cvelogic Threat Intelligence