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Fencer Intel
critical 9.8

CVE-2020-15917 json

common/session.c in Claws Mail before 3.17.6 has a protocol violation because suffix data after STARTTLS is mishandled.

published 6y ago modified 4mo ago also EUVD-2020-7889

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.6%
EPSS 2.6% chance of exploitation in 30 days, percentile 85%
public exploits
0
none known

Summary

common/session.c in Claws Mail before 3.17.6 has a protocol violation because suffix data after STARTTLS is mishandled.

Patch / fix

  • claws-mail claws-mail 3.17.6
  • claws-mail Debian 14, Debian 13, Debian 12 3.17.6-1

debian advisories DEBIAN-CVE-2020-15917

  • claws-mail openSUSE Tumbleweed 4.0.0-2.5
  • claws-mail Package Hub 15 SP3, Package Hub 15 SP2, openSUSE Leap 15.3 +1 more 3.18.0-bp153.2.3.1
  • claws-mail Package Hub 15 SP2, Package Hub 15 SP1, openSUSE Leap 15.2 +1 more 3.17.8-bp152.3.6.1
  • claws-mail Package Hub 15 SP1 3.17.3-bp151.3.3.1
  • claws-mail Package Hub 15 SP2 3.17.6-bp152.3.3.1
  • claws-mail openSUSE Leap 15.2 3.17.6-lp152.3.3.1
  • claws-mail openSUSE Leap 15.1 3.17.3-lp151.2.3.1

opensuse advisories openSUSE-SU-2024:10686-1openSUSE-SU-2021:1045-1openSUSE-SU-2020:1822-1openSUSE-SU-2020:1269-1openSUSE-SU-2020:1192-1openSUSE-SU-2020:1139-1

  • claws-mail Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 3.17.6-r0

alpine advisories ALPINE-CVE-2020-15917

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2020-15917 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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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-15917 updated cvss 9.1

claws-mail: protocol violation because suffix data after STARTTLS is mishandled

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.61% chance of exploitation in the next 30 days, higher than 85% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

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.