CVE-2026-12243

✕ Withdrawn — historical dataHIGHPre-NVD 7.5
7.5CVSS
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

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

NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issue #3504. The _UNSAFE_NO_PROTOCOL_RE regex in nltk/data.py checks for literal ../ sequences but fails to account for percent-encoded traversal sequences such as ..%2f. The url2pathname() function decodes these sequences after the validation step, allowing an attacker to bypass the protection. This vulnerability enables an attacker to read arbitrary files accessible to the Python process by controlling the resource name parameter passed to nltk.data.load() or nltk.data.find(). The issue affects applications that rely on NLTK for resource loading, including NLP web applications, Jupyter notebooks, and CLI tools. The default pathsec.ENFORCE=False setting exacerbates the impact by not blocking the file read at the open() stage.

CVSS v3
7.5
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Not yet assessedThis CVE record was withdrawn by its numbering authority, so there is no vulnerability to rate.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
1%
EPSS %ILE
45%
KEV
Not listed

Published

June 30, 2026

Last Modified

June 30, 2026

Advisory Details (1)

Auto-updated Jun 30, 2026
No patch confirmed yet.
generic

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Vendor Advisories for CVE-2026-12243(2)

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

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
nltk3.10.0-1 ... 3.9.3-1 (12 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
nltk3.10.0-1 ... 3.9.3-1 (8 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
nltk3.10.0-1, 3.10.1-1, 3.9.1-2, 3.9.2-1, 3.9.3-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
nltk3.10.0-1, 3.10.1-1, 3.9.1-2, 3.9.2-1, 3.9.3-1——
PyPI(1)
PackageVulnerable rangeFixed inDependents
nltk0.8 ... 3.9b1 (65 versions)——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 0× in last 7d / 69× 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.

Showing the most recent 100 of 142 total refreshes for this CVE.

  1. 2026-08-18 23:08 UTCEG score recompute▼ 7.50
  2. 2026-08-18 06:27 UTCEG score recompute
  3. 2026-08-16 18:14 UTCEG score recompute
  4. 2026-08-16 14:56 UTCEPSS rescore
  5. 2026-08-16 04:35 UTCEG score recompute
  6. 2026-08-16 02:14 UTCEPSS rescore
  7. 2026-08-15 02:18 UTCEG score recompute
  8. 2026-08-15 01:30 UTCEPSS rescore
  9. 2026-08-14 00:01 UTCEG score recompute
  10. 2026-08-13 22:00 UTCEPSS rescore
  11. 2026-08-13 10:51 UTCGHSA enrichment
  12. 2026-08-12 21:43 UTCEG score recompute
  13. 2026-08-12 21:43 UTCGHSA enrichment
  14. 2026-08-12 13:50 UTCEPSS rescore
  15. 2026-08-12 08:34 UTCGHSA enrichment
  16. 2026-08-11 19:25 UTCEG score recompute
  17. 2026-08-11 19:25 UTCGHSA enrichment
  18. 2026-08-11 13:42 UTCEPSS rescore
  19. 2026-08-11 06:16 UTCEG score recompute
  20. 2026-08-11 06:16 UTCGHSA enrichment
  21. 2026-08-10 23:59 UTCEPSS rescore
  22. 2026-08-10 17:08 UTCGHSA enrichment
  23. 2026-08-10 02:16 UTCEG score recompute
  24. 2026-08-10 02:16 UTCGHSA enrichment
  25. 2026-08-09 13:46 UTCEPSS rescore
Show 75 more
  1. 2026-08-09 13:08 UTCGHSA enrichment
  2. 2026-08-08 23:59 UTCEG score recompute
  3. 2026-08-08 23:59 UTCGHSA enrichment
  4. 2026-08-08 16:37 UTCEPSS rescore
  5. 2026-08-08 10:50 UTCGHSA enrichment
  6. 2026-08-07 21:41 UTCEG score recompute
  7. 2026-08-07 21:41 UTCGHSA enrichment
  8. 2026-08-07 08:32 UTCGHSA enrichment
  9. 2026-08-06 19:23 UTCEG score recompute
  10. 2026-08-06 19:23 UTCGHSA enrichment
  11. 2026-08-06 13:46 UTCEPSS rescore
  12. 2026-08-06 06:15 UTCEG score recompute
  13. 2026-08-06 06:15 UTCGHSA enrichment
  14. 2026-08-05 19:17 UTCEPSS rescore
  15. 2026-08-05 17:06 UTCGHSA enrichment
  16. 2026-08-05 03:55 UTCEG score recompute
  17. 2026-08-05 03:55 UTCGHSA enrichment
  18. 2026-08-04 15:09 UTCEPSS rescore
  19. 2026-08-04 14:44 UTCEG score recompute
  20. 2026-08-04 14:44 UTCGHSA enrichment
  21. 2026-08-04 10:38 UTCEPSS rescore
  22. 2026-08-03 22:09 UTCEG score recompute
  23. 2026-08-03 22:09 UTCGHSA enrichment
  24. 2026-08-03 10:35 UTCEPSS rescore
  25. 2026-08-03 09:00 UTCGHSA enrichment
  26. 2026-08-02 19:51 UTCGHSA enrichment
  27. 2026-08-02 06:43 UTCEG score recompute
  28. 2026-08-02 06:43 UTCGHSA enrichment
  29. 2026-08-02 02:26 UTCEPSS rescore
  30. 2026-08-01 17:34 UTCGHSA enrichment
  31. 2026-08-01 04:25 UTCEG score recompute
  32. 2026-08-01 04:25 UTCGHSA enrichment
  33. 2026-08-01 04:15 UTCEPSS rescore
  34. 2026-07-31 15:16 UTCGHSA enrichment
  35. 2026-07-31 02:06 UTCEG score recompute
  36. 2026-07-31 02:06 UTCGHSA enrichment
  37. 2026-07-30 16:27 UTCEPSS rescore
  38. 2026-07-30 12:20 UTCEG score recompute
  39. 2026-07-30 12:20 UTCGHSA enrichment
  40. 2026-07-30 01:30 UTCEPSS rescore
  41. 2026-07-29 22:29 UTCGHSA enrichment
  42. 2026-07-29 08:51 UTCGHSA enrichment
  43. 2026-07-28 19:42 UTCEG score recompute
  44. 2026-07-28 19:42 UTCGHSA enrichment
  45. 2026-07-28 15:36 UTCEPSS rescore
  46. 2026-07-28 06:01 UTCGHSA enrichment
  47. 2026-07-27 16:52 UTCEG score recompute
  48. 2026-07-27 16:52 UTCGHSA enrichment
  49. 2026-07-27 14:13 UTCEPSS rescore
  50. 2026-07-27 03:09 UTCEG score recompute
  51. 2026-07-27 03:09 UTCGHSA enrichment
  52. 2026-07-26 14:54 UTCEPSS rescore
  53. 2026-07-26 14:54 UTCEPSS rescore
  54. 2026-07-26 13:57 UTCEG score recompute
  55. 2026-07-26 13:57 UTCGHSA enrichment
  56. 2026-07-25 14:17 UTCEPSS rescore
  57. 2026-07-24 14:17 UTCEPSS rescore
  58. 2026-07-23 14:18 UTCEPSS rescore
  59. 2026-07-23 03:05 UTCEG score recompute
  60. 2026-07-22 14:08 UTCEPSS rescore
  61. 2026-07-21 15:24 UTCEPSS rescore
  62. 2026-07-20 17:08 UTCEPSS rescore
  63. 2026-07-19 14:30 UTCEPSS rescore
  64. 2026-07-19 02:28 UTCEPSS rescore
  65. 2026-07-18 10:04 UTCEPSS rescore
  66. 2026-07-17 02:15 UTCGHSA enrichment
  67. 2026-07-16 17:02 UTCEPSS rescore
  68. 2026-07-16 12:43 UTCGHSA enrichment
  69. 2026-07-15 23:33 UTCGHSA enrichment
  70. 2026-07-15 16:57 UTCEPSS rescore
  71. 2026-07-15 10:25 UTCGHSA enrichment
  72. 2026-07-15 02:00 UTCEPSS rescore
  73. 2026-07-14 21:16 UTCGHSA enrichment
  74. 2026-07-14 08:07 UTCGHSA enrichment
  75. 2026-07-13 22:30 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-12243?
CVE-2026-12243 is a high vulnerability published on June 30, 2026. NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issue #3504. The UNSAFENOPROTOCOLRE regex in nltk/data.py checks for literal ../ sequences but fails to account for percent-encoded traversal sequences such as ..%2f. The url2pathname() function decodes…
When was CVE-2026-12243 disclosed?
CVE-2026-12243 was first published in the National Vulnerability Database on June 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-12243 actively exploited?
CVE-2026-12243 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.9% of all scored CVEs.
What is the CVSS score of CVE-2026-12243?
CVE-2026-12243 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-12243?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-12243, 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

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