CVE-2021-38502

MEDIUMNVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

Score 5.9 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 5.9Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
—
EPSS
61.2%
KEV
Not listed

Published

November 3, 2021

Last Modified

November 21, 2024

References (8)

Vendor Advisories for CVE-2021-38502(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuthunderbird-locale-id (1:91.5.0+build1-0ubuntu0.20.04.1) @ focal2026-05-26ubuntu
redhatthunderbird-0:91.2.0-1.el7_92021-10-13redhat
redhatthunderbird-0:91.2.0-1.el8_42021-10-13redhat
redhatthunderbird-0:91.2.0-1.el8_12021-10-13redhat
redhatthunderbird-0:91.2.0-1.el8_22021-10-13redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(4)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 14× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 22:50 UTCEG score recompute
  2. 2026-07-22 14:06 UTCEPSS rescore
  3. 2026-07-22 14:06 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
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  11. 2026-07-18 10:02 UTCEPSS rescore
  12. 2026-07-18 08:59 UTCOSV refresh
  13. 2026-07-16 17:00 UTCEPSS rescore
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  15. 2026-07-15 16:55 UTCEPSS rescore
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  21. 2026-07-11 08:25 UTCEPSS rescore
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  25. 2026-07-07 13:43 UTCEPSS rescore
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  1. 2026-07-06 16:25 UTCEPSS rescore
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  5. 2026-07-04 06:29 UTCEPSS rescore
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  7. 2026-07-01 15:04 UTCEPSS rescore
  8. 2026-06-30 23:20 UTCEPSS rescore
  9. 2026-06-30 23:20 UTCEPSS rescore
  10. 2026-06-30 08:00 UTCOSV refresh
  11. 2026-06-29 14:04 UTCEPSS rescore
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  20. 2026-06-23 21:31 UTCEPSS rescore
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  22. 2026-06-22 14:24 UTCEPSS rescore
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  24. 2026-06-21 14:55 UTCEPSS rescore
  25. 2026-06-21 01:58 UTCEPSS rescore
  26. 2026-06-21 01:58 UTCEPSS rescore
  27. 2026-06-19 19:24 UTCEPSS rescore
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  29. 2026-06-18 17:51 UTCEPSS rescore
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  35. 2026-06-14 23:15 UTCEPSS rescore
  36. 2026-06-13 22:58 UTCEPSS rescore
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  38. 2026-06-12 23:10 UTCEPSS rescore
  39. 2026-06-12 23:10 UTCEPSS rescore
  40. 2026-06-12 17:40 UTCOSV refresh
  41. 2026-06-11 13:58 UTCEPSS rescore
  42. 2026-06-10 22:16 UTCEPSS rescore
  43. 2026-06-10 13:20 UTCEPSS rescore
  44. 2026-06-08 14:15 UTCEPSS rescore
  45. 2026-06-08 14:15 UTCEPSS rescore
  46. 2026-06-07 15:23 UTCEPSS rescore
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  48. 2026-06-06 13:46 UTCEPSS rescore
  49. 2026-06-06 13:46 UTCEPSS rescore
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  51. 2026-06-05 22:45 UTCEPSS rescore
  52. 2026-06-05 06:09 UTCEPSS rescore
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  54. 2026-06-04 13:10 UTCEPSS rescore
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  58. 2026-05-31 22:29 UTCEPSS rescore
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  60. 2026-05-31 00:15 UTCEPSS rescore
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  62. 2026-05-29 13:42 UTCEPSS rescore
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  69. 2026-05-26 13:42 UTCEPSS rescore
  70. 2026-05-26 08:07 UTCEG score recompute
  71. 2026-05-26 08:07 UTCVendor advisory
  72. 2026-05-26 08:07 UTCGHSA enrichment
  73. 2026-05-26 07:17 UTCEPSS rescore
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Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-38502?
CVE-2021-38502 is a medium vulnerability published on November 3, 2021. 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…
When was CVE-2021-38502 disclosed?
CVE-2021-38502 was first published in the National Vulnerability Database on November 3, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-38502 actively exploited?
CVE-2021-38502 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 61.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-38502?
CVE-2021-38502 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2021-38502?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-38502, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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