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Fencer Vulns
high 8.8

CVE-2020-15685 json

During the plaintext phase of the STARTTLS connection setup, protocol commands could have been injected and evaluated within the encrypted…

published 2022-12-22 3 y ago modified 2026-06-17 4 mo ago also EUVD-2020-7672

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

During the plaintext phase of the STARTTLS connection setup, protocol commands could have been injected and evaluated within the encrypted session. This vulnerability affects Thunderbird < 78.7.

Patch / fix

  • Mozilla Thunderbird 78.7
  • thunderbird Debian 14, Debian 13, Debian 12 1:78.7.0-1

debian advisories DEBIAN-CVE-2020-15685

  • thunderbird Ubuntu 18.04 LTS 1:78.8.1+build1-0ubuntu0.18.04.1
  • thunderbird Ubuntu 20.04 LTS 1:78.7.1+build1-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2020-15685

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

  • thunderbird RHEL 7 78.7.0-1.el7_9
  • thunderbird RHEL 8 78.7.0-1.el8_3
  • thunderbird RHEL 8.1 EUS 78.7.0-1.el8_1
  • thunderbird RHEL 8.2 EUS 78.7.0-1.el8_2

red hat advisories RHSA-2021:0397RHSA-2021:0297RHSA-2021:0298RHSA-2021:0299

  • MozillaThunderbird SLE Workstation Extension 15 SP2 78.7.0-8.9.1
  • MozillaThunderbird SLE Workstation Extension 15 SP1 78.7.0-3.119.1

suse advisories SUSE-SU-2021:0257-1SUSE-SU-2021:0245-1

  • MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1
  • MozillaThunderbird openSUSE Leap 15.2 78.7.0-lp152.2.29.1
  • MozillaThunderbird openSUSE Leap 15.1 78.7.0-lp151.2.69.1

opensuse advisories openSUSE-SU-2024:10601-1openSUSE-SU-2021:0209-1openSUSE-SU-2021:0208-1

  • thunderbird Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 78.7.0-r0

alpine advisories ALPINE-CVE-2020-15685

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

  • thunderbird Arch Linux 78.7.0-1

arch linux advisories AVG-1496

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-2020-15685 updated cvss 8.8

Mozilla: IMAP Response Injection when using STARTTLS

  • Red Hat Enterprise Linux 6 thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) thunderbird 78.7.0-1.el8_3
    fixed: vendor fix RHSA-2021:0298
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird 78.7.0-1.el8_1
    fixed: vendor fix RHSA-2021:0397
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird 78.7.0-1.el8_2
    fixed: vendor fix RHSA-2021:0299
  • Red Hat Enterprise Linux Client (v. 7) thunderbird 78.7.0-1.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) thunderbird 78.7.0-1.el7_9 Red Hat Enterprise Linux Workstation (v. 7) thunderbird 78.7.0-1.el7_9
    fixed: vendor fix RHSA-2021:0297

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

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
18 mo ago

Exploit prediction

0.88% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1622640 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • Mozilla Thunderbird

Classification

Weakness
  • CWE-77 Improper Neutralization of Special Elements used in a Command

References

Sources

Fencer Vulns 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.