CVE-2016-0772

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2022-05-14. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 15%CVSS: 6.5Exploit: NoneExposed: 0

A fix is available — apply it.

The smtplib library in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 does not return an error when StartTLS fails, which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command, aka a "StartTLS stripping attack."

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity65% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
96.3%
KEV
Not listed

Published

September 2, 2016

Last Modified

May 6, 2026

References (36)

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython3.5-venv (3.5.2-2ubuntu0~16.04.1) @ xenial2026-05-22ubuntu
redhatpython-0:2.7.5-38.el7_22016-08-18redhat
redhatpython27-python-0:2.7.8-16.el72016-08-18redhat
redhatpython33-python-0:3.3.2-16.el72016-08-18redhat
redhatrh-python34-python-0:3.4.2-13.el72016-08-18redhat
redhatrh-python35-python-0:3.5.1-9.el72016-08-18redhat

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.

All Vendor Advisories

(6)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 11× in last 7d / 38× 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. 2026-07-24 14:13 UTCEPSS rescore
  2. 2026-07-23 14:14 UTCEPSS rescore
  3. 2026-07-23 01:21 UTCEG score recompute
  4. 2026-07-23 00:22 UTCEG score recompute
  5. 2026-07-22 22:00 UTCEG score recompute
  6. 2026-07-22 14:04 UTCEPSS rescore
  7. 2026-07-21 15:21 UTCEPSS rescore
  8. 2026-07-21 15:21 UTCEPSS rescore
  9. 2026-07-20 17:03 UTCEPSS rescore
  10. 2026-07-19 02:26 UTCEPSS rescore
  11. 2026-07-19 02:26 UTCEPSS rescore
  12. 2026-07-18 10:00 UTCEPSS rescore
  13. 2026-07-16 16:59 UTCEPSS rescore
  14. 2026-07-15 16:54 UTCEPSS rescore
  15. 2026-07-15 16:54 UTCEPSS rescore
  16. 2026-07-15 01:56 UTCEPSS rescore
  17. 2026-07-13 22:26 UTCEPSS rescore
  18. 2026-07-13 22:26 UTCEPSS rescore
  19. 2026-07-12 08:07 UTCOSV refresh
  20. 2026-07-12 05:42 UTCEPSS rescore
  21. 2026-07-11 08:23 UTCEPSS rescore
  22. 2026-07-09 19:05 UTCEPSS rescore
  23. 2026-07-09 19:05 UTCEPSS rescore
  24. 2026-07-08 15:10 UTCEPSS rescore
  25. 2026-07-07 13:42 UTCEPSS rescore
Show 72 more
  1. 2026-07-07 13:42 UTCEPSS rescore
  2. 2026-07-05 02:26 UTCEPSS rescore
  3. 2026-07-04 06:28 UTCEPSS rescore
  4. 2026-07-01 15:02 UTCEPSS rescore
  5. 2026-06-30 23:19 UTCEPSS rescore
  6. 2026-06-30 23:19 UTCEPSS rescore
  7. 2026-06-29 14:03 UTCEPSS rescore
  8. 2026-06-29 14:03 UTCEPSS rescore
  9. 2026-06-28 14:04 UTCEPSS rescore
  10. 2026-06-28 04:53 UTCEPSS rescore
  11. 2026-06-27 03:05 UTCEPSS rescore
  12. 2026-06-25 13:47 UTCEPSS rescore
  13. 2026-06-25 13:47 UTCEPSS rescore
  14. 2026-06-24 14:02 UTCEPSS rescore
  15. 2026-06-24 14:02 UTCEPSS rescore
  16. 2026-06-23 21:30 UTCEPSS rescore
  17. 2026-06-23 13:30 UTCOSV refresh
  18. 2026-06-21 14:54 UTCEPSS rescore
  19. 2026-06-21 14:54 UTCEPSS rescore
  20. 2026-06-21 01:57 UTCEPSS rescore
  21. 2026-06-21 01:57 UTCEPSS rescore
  22. 2026-06-18 17:50 UTCEPSS rescore
  23. 2026-06-17 17:50 UTCEPSS rescore
  24. 2026-06-17 17:49 UTCEPSS rescore
  25. 2026-06-16 17:50 UTCEPSS rescore
  26. 2026-06-16 17:50 UTCEPSS rescore
  27. 2026-06-15 17:45 UTCEPSS rescore
  28. 2026-06-14 23:14 UTCEPSS rescore
  29. 2026-06-13 22:57 UTCEPSS rescore
  30. 2026-06-12 23:09 UTCEPSS rescore
  31. 2026-06-12 23:09 UTCEPSS rescore
  32. 2026-06-11 13:57 UTCEPSS rescore
  33. 2026-06-11 13:57 UTCEPSS rescore
  34. 2026-06-10 22:15 UTCEPSS rescore
  35. 2026-06-10 13:18 UTCEPSS rescore
  36. 2026-06-08 14:14 UTCEPSS rescore
  37. 2026-06-07 15:22 UTCEPSS rescore
  38. 2026-06-06 15:59 UTCOSV refresh
  39. 2026-06-06 13:45 UTCEPSS rescore
  40. 2026-06-05 22:44 UTCEPSS rescore
  41. 2026-06-05 06:08 UTCEPSS rescore
  42. 2026-06-05 06:08 UTCEPSS rescore
  43. 2026-06-04 13:10 UTCEPSS rescore
  44. 2026-06-04 13:10 UTCEPSS rescore
  45. 2026-06-02 20:10 UTCEPSS rescore
  46. 2026-06-01 13:49 UTCEPSS rescore
  47. 2026-06-01 13:49 UTCEPSS rescore
  48. 2026-05-31 22:28 UTCEPSS rescore
  49. 2026-05-31 22:28 UTCEPSS rescore
  50. 2026-05-31 00:14 UTCEPSS rescore
  51. 2026-05-29 13:41 UTCEPSS rescore
  52. 2026-05-28 13:42 UTCEPSS rescore
  53. 2026-05-28 13:42 UTCEPSS rescore
  54. 2026-05-27 13:38 UTCEPSS rescore
  55. 2026-05-27 13:38 UTCEPSS rescore
  56. 2026-05-26 13:41 UTCEPSS rescore
  57. 2026-05-26 07:16 UTCEPSS rescore
  58. 2026-05-26 07:16 UTCEPSS rescore
  59. 2026-05-24 16:43 UTCEPSS rescore
  60. 2026-05-22 21:15 UTCEPSS rescore
  61. 2026-05-22 18:57 UTCEG score recompute
  62. 2026-05-22 18:57 UTCVendor advisory
  63. 2026-05-22 18:57 UTCGHSA enrichment
  64. 2026-05-22 17:43 UTCOSV refresh
  65. 2026-05-21 22:40 UTCEPSS rescore
  66. 2026-05-20 22:37 UTCEPSS rescore
  67. 2026-05-20 22:37 UTCEPSS rescore
  68. 2026-05-20 11:21 UTCEPSS rescore
  69. 2026-05-20 11:21 UTCEPSS rescore
  70. 2026-05-20 11:21 UTCEPSS rescore
  71. 2026-05-18 21:30 UTCEPSS rescore
  72. 2026-05-18 21:30 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-43500
    First seen Jul 3, 2016

    Python smtplib 2.7.11 / 3.4.4 / 3.5.1 - Man In The Middle StartTLS Stripping

    Open source ↗

Frequently asked(5)

What is CVE-2016-0772?
CVE-2016-0772 is a medium vulnerability published on September 2, 2016. The smtplib library in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 does not return an error when StartTLS fails, which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block…
When was CVE-2016-0772 disclosed?
CVE-2016-0772 was first published in the National Vulnerability Database on September 2, 2016, with the most recent update on May 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-0772 actively exploited?
CVE-2016-0772 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 96.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-0772?
CVE-2016-0772 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2016-0772?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-0772, 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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