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Fencer Intel
medium 5.9

CVE-2021-46853 json

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

published 4y ago modified 4mo ago also EUVD-2021-33507

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 67%
public exploits
0
none known

Summary

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

Patch / fix

  • alpine_project alpine 2.25
  • alpine Debian 14, Debian 13, Debian 12 2.25+dfsg1-1

debian advisories DEBIAN-CVE-2021-46853

  • alpine Ubuntu Pro 16.04 LTS 2.20+dfsg1-2ubuntu0.1~esm1
  • alpine Ubuntu Pro 18.04 LTS 2.21+dfsg1-1ubuntu0.1~esm1
  • alpine Ubuntu Pro 20.04 LTS 2.22+dfsg1-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-46853

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2021-46853 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

1.15% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.