CVE-2026-78683

CRITICALPre-NVD 9.69.6
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 9.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (43rd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Trending — 4 sources updated this weekElevated

Also known asEUVD-2026-65229 (ENISA EUVD) · GHSA-gx65-c5hj-vpv5 (GitHub Security Advisories) · GHSA-rhp5-r9x4-f5g2 (GitHub Security Advisories)Source: ENISA EUVD

9.6EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.6Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

NLTK before 3.10.0 (affected versions <=3.9.4) contains an unsafe pickle deserialization vulnerability in the TransitionParser.parse() method (nltk/parse/transitionparser.py). The method calls pickle_load() with the default restricted=False, routing deserialization through WarningUnpickler, which does not override find_class() and therefore permits arbitrary class resolution. When an application loads an attacker-crafted model file, embedded pickle gadget chains execute arbitrary Python code with the privileges of the user running the application. NLTK provides a RestrictedUnpickler for safe deserialization, but it is not used by production code paths. Fixed in 3.10.0.

CVSS v3
9.6
EG Score
9.6CRITICALmedium confidence
EG Risk
59
EG Risk 59/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity96% × 45%
Impact severity (EG Severity): CVSS 9.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
43rd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.6): severity, escalated by confirmed exploitation. This CVE's 9.6 is its impact severity (EG Severity), not escalated.

EG Severity
9.6 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 25, 2026

Last Modified

October 12, 2026

Advisory Details (2)

Auto-updated Oct 7, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

[CWE-502] Unsafe Pickle Deserialization in TransitionParser Allows Remote Code Execution · Advisory · nltk/nltk · GitHub

Affected: 3.10.0+.

https://github.com/nltk/nltk/security/advisories/GHSA-rhp5-r9x4-f5g2
Web page

NLTK before 3.10.0 Remote Code Execution via Unsafe Pickle Deserialization | Advisories | VulnCheck

https://www.vulncheck.com/advisories/nltk-before-remote-code-execution-via-unsafe-pickle-deserialization

Vendor Advisories for CVE-2026-78683(2)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrhoai/odh-trustyai-garak-lls-provider-dsp-rhel9:17917858042026-10-19redhat
pipnltk @ 3.10.0 (fixes <= 3.9.4)—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 rangeFix by version rangeDependents
nltk3.10.0-1 ... 3.9.3-1 (9 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
nltk3.10.0-1 ... 3.9.3-1 (6 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
nltk3.9.1-2, 3.9.2-1, 3.9.3-1
  • every version up to 3.10.0-1: fixed in 3.10.0-1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
nltk0.8 ... 3.9b1 (65 versions)
  • every version up to 3.10.0: fixed in 3.10.0
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 77× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 199 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 99 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  2. 2026-11-01 15:24 UTCVendor advisory
  3. 2026-11-01 15:24 UTCGHSA enrichmentGHSA-rhp5-r9x4-f5g2 · GitHub severity CRITICAL
  4. 2026-11-01 07:38 UTCGHSA enrichmentGHSA-rhp5-r9x4-f5g2 · GitHub severity CRITICAL
  5. 2026-11-01 07:38 UTCEG score recompute
  6. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  7. 2026-10-31 13:48 UTCEG score recompute
  8. 2026-10-31 13:48 UTCVendor advisory
  9. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  10. 2026-10-30 12:12 UTCEG score recompute
  11. 2026-10-30 12:12 UTCVendor advisory
  12. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  13. 2026-10-29 10:36 UTCEG score recompute
  14. 2026-10-29 10:36 UTCVendor advisory
  15. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  16. 2026-10-28 08:58 UTCEG score recompute
  17. 2026-10-28 08:58 UTCVendor advisory
  18. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  19. 2026-10-27 06:48 UTCEG score recompute
  20. 2026-10-27 06:48 UTCVendor advisory
  21. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  22. 2026-10-26 01:46 UTCEG score recompute
  23. 2026-10-26 01:46 UTCVendor advisory
  24. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  25. 2026-10-25 14:00 UTCEG score recompute
Show 75 more
  1. 2026-10-25 00:10 UTCEG score recompute
  2. 2026-10-25 00:10 UTCVendor advisory
  3. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  4. 2026-10-23 22:34 UTCEG score recompute
  5. 2026-10-23 22:34 UTCVendor advisory
  6. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  7. 2026-10-22 20:51 UTCEG score recompute
  8. 2026-10-22 20:51 UTCVendor advisory
  9. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  10. 2026-10-21 19:15 UTCEG score recompute
  11. 2026-10-21 19:15 UTCVendor advisory
  12. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  13. 2026-10-20 17:40 UTCEG score recompute
  14. 2026-10-20 17:40 UTCVendor advisory
  15. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  16. 2026-10-20 09:44 UTCEG score recompute
  17. 2026-10-20 09:44 UTCVendor advisory
  18. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  19. 2026-10-19 08:07 UTCEG score recompute
  20. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  21. 2026-10-18 03:11 UTCEG score recompute
  22. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  23. 2026-10-17 04:50 UTCEG score recompute
  24. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  25. 2026-10-16 03:13 UTCEG score recompute
  26. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  27. 2026-10-14 23:16 UTCEG score recompute
  28. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  29. 2026-10-13 19:05 UTCEG score recompute
  30. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  31. 2026-10-12 17:25 UTCEG score recompute
  32. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  33. 2026-10-12 15:36 UTCEG score recompute
  34. 2026-10-11 19:22 UTCEG score recompute
  35. 2026-10-11 16:38 UTCEG score recompute
  36. 2026-10-11 13:57 UTCEG score recompute
  37. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  38. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  39. 2026-10-10 12:24 UTCEG score recompute
  40. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  41. 2026-10-09 04:36 UTCEG score recompute
  42. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  43. 2026-10-08 03:39 UTCEG score recompute
  44. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  45. 2026-10-06 16:09 UTCEG score recompute
  46. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  47. 2026-10-05 18:02 UTCEG score recompute
  48. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  49. 2026-10-05 01:25 UTCEG score recompute
  50. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  51. 2026-10-03 16:28 UTCEG score recompute
  52. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  53. 2026-10-02 19:23 UTCEG score recompute
  54. 2026-10-01 20:59 UTCEG score recompute
  55. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  56. 2026-09-30 20:16 UTCEG score recompute
  57. 2026-09-30 06:55 UTCEG score recompute
  58. 2026-09-29 15:24 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  59. 2026-09-28 21:31 UTCEG score recompute
  60. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  61. 2026-09-27 15:41 UTCEG score recompute
  62. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  63. 2026-09-26 22:11 UTCEG score recompute
  64. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  65. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  66. 2026-09-24 18:53 UTCEG score recompute
  67. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  68. 2026-09-24 04:50 UTCEG score recompute
  69. 2026-09-23 20:31 UTCEG score recompute
  70. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  71. 2026-09-22 19:22 UTCEG score recompute
  72. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  73. 2026-09-21 22:30 UTCEG score recompute
  74. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  75. 2026-09-20 21:15 UTCEG score recompute

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-78683?
CVE-2026-78683 is a critical-severity vulnerability; its CVE record was published on August 25, 2026. NLTK before 3.10.0 (affected versions <=3.9.4) contains an unsafe pickle deserialization vulnerability in the TransitionParser.parse() method (nltk/parse/transitionparser.py). The method calls pickle_load() with the default restricted=False, routing deserialization through WarningUnpickler, which…
When was CVE-2026-78683 made public?
CVE-2026-78683 was made public on August 11, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on August 25, 2026. EchelonGraph's copy of the record carries a last-modified date of October 12, 2026; the record at its source may have been updated since.
Is CVE-2026-78683 actively exploited?
CVE-2026-78683 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (43rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-78683?
CVE-2026-78683 has a CVSS base score of 9.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-78683?
A fix for CVE-2026-78683 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-78683 are linked in the Vendor Advisories panel on this page.

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