CVE-2026-63310

✕ Withdrawn — historical dataMEDIUMNVD 6.5Elevated
6.5CVSS
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.

CVSS v3
6.5
EchelonGraph score
Not yet assessedThis CVE record was withdrawn by its numbering authority, so there is no vulnerability to rate.
EG Score
—
EG Risk
—
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

August 22, 2026

Last Modified

August 31, 2026

Advisory Details (2)

Auto-updated Aug 22, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

NLTK before 3.9.3 Missing Post-Download Integrity Verification | Advisories | VulnCheck

https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification
github Patch Available🟡 PoC Available

Missing Post-Download Integrity Verification Allows Malicious Package Injection · Advisory · nltk/nltk · GitHub

https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q

Vendor Advisories for CVE-2026-63310(1)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
pipnltk—ghsa

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.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
nltk3.10.0-1 ... 3.9.3-1 (9 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
nltk3.10.0-1 ... 3.9.3-1 (6 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
nltk3.9.1-2, 3.9.2-13.9.3-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
nltk0.8 ... 3.9b1 (63 versions)3.9.3—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 96× 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. 2026-09-18 05:46 UTCGHSA enrichment
  2. 2026-09-15 06:19 UTCEG score recompute▼ 7.10
  3. 2026-09-15 06:19 UTCGHSA enrichment
  4. 2026-09-14 19:04 UTCGHSA enrichment
  5. 2026-09-14 07:38 UTCGHSA enrichment
  6. 2026-09-13 20:24 UTCEG score recompute
  7. 2026-09-13 20:24 UTCGHSA enrichment
  8. 2026-09-13 09:09 UTCGHSA enrichment
  9. 2026-09-12 21:55 UTCGHSA enrichment
  10. 2026-09-12 10:40 UTCGHSA enrichment
  11. 2026-09-11 23:25 UTCEG score recompute
  12. 2026-09-11 23:25 UTCGHSA enrichment
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 12:05 UTCEG score recompute
  15. 2026-09-11 12:05 UTCGHSA enrichment
  16. 2026-09-11 09:37 UTCEPSS rescore
  17. 2026-09-11 00:16 UTCGHSA enrichment
  18. 2026-09-10 12:12 UTCEG score recompute
  19. 2026-09-10 12:12 UTCGHSA enrichment
  20. 2026-09-10 00:41 UTCGHSA enrichment
  21. 2026-09-09 12:57 UTCGHSA enrichment
  22. 2026-09-09 01:42 UTCEG score recompute
  23. 2026-09-09 01:42 UTCGHSA enrichment
  24. 2026-09-08 22:01 UTCEPSS rescore
  25. 2026-09-08 08:00 UTCGHSA enrichment
Show 71 more
  1. 2026-09-07 20:45 UTCGHSA enrichment
  2. 2026-09-07 09:31 UTCGHSA enrichment
  3. 2026-09-06 21:55 UTCEG score recompute
  4. 2026-09-06 21:55 UTCGHSA enrichment
  5. 2026-09-06 13:47 UTCEPSS rescore
  6. 2026-09-06 10:32 UTCGHSA enrichment
  7. 2026-09-05 23:18 UTCEG score recompute
  8. 2026-09-05 23:18 UTCGHSA enrichment
  9. 2026-09-05 15:31 UTCEPSS rescore
  10. 2026-09-05 12:03 UTCGHSA enrichment
  11. 2026-09-05 00:48 UTCEG score recompute
  12. 2026-09-05 00:47 UTCGHSA enrichment
  13. 2026-09-04 13:32 UTCEG score recompute
  14. 2026-09-04 13:32 UTCGHSA enrichment
  15. 2026-09-04 05:07 UTCEPSS rescore
  16. 2026-09-04 02:09 UTCGHSA enrichment
  17. 2026-09-03 14:53 UTCGHSA enrichment
  18. 2026-09-03 03:30 UTCGHSA enrichment
  19. 2026-09-02 16:05 UTCEG score recompute
  20. 2026-09-02 16:05 UTCGHSA enrichment
  21. 2026-09-02 14:12 UTCEPSS rescore
  22. 2026-09-02 04:49 UTCGHSA enrichment
  23. 2026-09-01 17:29 UTCEG score recompute
  24. 2026-09-01 17:29 UTCGHSA enrichment
  25. 2026-09-01 13:54 UTCEPSS rescore
  26. 2026-09-01 06:12 UTCEG score recompute
  27. 2026-09-01 06:12 UTCGHSA enrichment
  28. 2026-09-01 04:40 UTCEPSS rescore
  29. 2026-08-31 18:57 UTCEG score recompute
  30. 2026-08-31 18:57 UTCGHSA enrichment
  31. 2026-08-31 18:49 UTCNVD updateCVSS v3 → 6.5 · severity → MEDIUM
  32. 2026-08-31 14:45 UTCGHSA enrichment
  33. 2026-08-31 03:23 UTCEG score recompute
  34. 2026-08-31 03:23 UTCGHSA enrichment
  35. 2026-08-30 19:17 UTCEPSS rescore
  36. 2026-08-30 16:09 UTCGHSA enrichment
  37. 2026-08-30 04:55 UTCEG score recompute
  38. 2026-08-30 04:55 UTCGHSA enrichment
  39. 2026-08-30 01:22 UTCEPSS rescore
  40. 2026-08-29 17:41 UTCGHSA enrichment
  41. 2026-08-29 06:24 UTCEG score recompute
  42. 2026-08-29 06:24 UTCGHSA enrichment
  43. 2026-08-28 21:42 UTCEPSS rescore
  44. 2026-08-28 19:09 UTCGHSA enrichment
  45. 2026-08-28 14:55 UTCGHSA enrichment
  46. 2026-08-28 03:39 UTCGHSA enrichment
  47. 2026-08-27 16:25 UTCEG score recompute
  48. 2026-08-27 16:25 UTCGHSA enrichment
  49. 2026-08-27 14:25 UTCEPSS rescore
  50. 2026-08-27 05:06 UTCGHSA enrichment
  51. 2026-08-26 17:51 UTCEG score recompute
  52. 2026-08-26 17:51 UTCGHSA enrichment
  53. 2026-08-26 14:46 UTCEPSS rescore
  54. 2026-08-26 06:10 UTCGHSA enrichment
  55. 2026-08-25 18:55 UTCEG score recompute
  56. 2026-08-25 18:55 UTCGHSA enrichment
  57. 2026-08-25 13:49 UTCEPSS rescore
  58. 2026-08-25 07:41 UTCGHSA enrichment
  59. 2026-08-24 20:27 UTCEG score recompute
  60. 2026-08-24 20:26 UTCGHSA enrichment
  61. 2026-08-24 19:22 UTCEG score recompute
  62. 2026-08-24 19:22 UTCGHSA enrichment
  63. 2026-08-24 12:28 UTCEG score recompute
  64. 2026-08-24 12:28 UTCGHSA enrichment
  65. 2026-08-24 01:07 UTCGHSA enrichment
  66. 2026-08-23 13:53 UTCGHSA enrichment
  67. 2026-08-23 02:38 UTCEG score recompute
  68. 2026-08-23 02:38 UTCGHSA enrichment
  69. 2026-08-22 15:24 UTCEG score recompute
  70. 2026-08-22 14:26 UTCEG score recompute
  71. 2026-08-22 14:25 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-63310?
CVE-2026-63310 is a medium vulnerability published on August 22, 2026. NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.
When was CVE-2026-63310 disclosed?
CVE-2026-63310 was first published in the National Vulnerability Database on August 22, 2026, with the most recent update on August 31, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63310 actively exploited?
CVE-2026-63310 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 98.2% of all scored CVEs.
What is the CVSS score of CVE-2026-63310?
CVE-2026-63310 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-63310?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63310, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-63310

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