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TI-2021-16102 Aliases CVE-2021-38502GHSA-wf24-4m95-7wjm

Thunderbird ignored the configuration to require STARTTLS security for an SMTP connection.

Priority LOW 29Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · None · None
Fix status
Partial Red Hat: 6 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

Thunderbird ignored the configuration to require STARTTLS security for an SMTP connection. A MITM could perform a downgrade attack to intercept transmitted messages, or could take control of the authenticated session to execute SMTP commands chosen by the MITM. If an unprotected authentication method was configured, the MITM could obtain the authentication credentials, too. This vulnerability affects Thunderbird < 91.2.

Why it matters now

EPSS 0.01101 65th percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 91.2Red Hat: 4 advisoriesRed Hat: 6 fixed, 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MozillaThunderbirdbefore 91.291.2Patch availableCNA
  • Thunderbird VendorMozilla Affected before 91.2 Fixed in 91.2 Patch available CNA

CPE configurations NVD · 4

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 91.2VulnerableMozilla
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*9.0VulnerableDebian
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*10.0VulnerableDebian
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*11.0VulnerableDebian
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 91.2 Vulnerable ·Mozilla
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
  • cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
  • cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian

Remediation

  • Fix · CNA Thunderbird (Mozilla) Fixed in 91.2

Red Hat 4 advisories

  • RHSA-2021:3841 Released 2021-10-13 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux Client (v. 7) thunderbird-91.2.0-1.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-91.2.0-1.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) thunderbird-91.2.0-1.el7_9
  • RHSA-2021:3838 Released 2021-10-13 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 8) thunderbird-91.2.0-1.el8_4
  • RHSA-2021:3839 Released 2021-10-13 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-91.2.0-1.el8_2
Show 1 more Red Hat advisories
  • RHSA-2021:3840 Released 2021-10-13 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-91.2.0-1.el8_1

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Mozilla Thunderbird 91.2

    4 records Highest priority Priority MEDIUM 1 MEDIUM, 3 LOW

    Other records, highest priority first

    • TI-2021-16101 Mozilla developers reported memory safety bugs present in Firefox 92 and Firefox ESR 91.1.Priority MEDIUM 40
    • TI-2021-16098 Use after free in Mozilla FirefoxPriority LOW 36
    • TI-2021-16097 Origin validation error in Mozilla FirefoxPriority LOW 30
    Show all 4 records →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2021:3838
Red Hat Enterprise Linux AppStream EUS (v. 8.1)Fixed RHSA-2021:3840
Red Hat Enterprise Linux AppStream EUS (v. 8.2)Fixed RHSA-2021:3839
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2021:3841
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2021:3841
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:3841

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-38502
  2. 2026-10-03 Alias added: GHSA-wf24-4m95-7wjm

References

Advisory 4

  • TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
  • TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
  • TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
  • TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
  • TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
See all 2067 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences