CVE-2026-80206

MEDIUMPre-NVD 5.95.9
EchelonGraph scoreMEDIUM confidence

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

Score 5.9 from GitHub Security Advisory (severity: HIGH) published 2026-08-31. A secondary CVSS source baseline 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Elevated
5.9EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (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: 0.4%CVSS: 5.9Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep module. The _tgrep_node_action function compiles user-supplied regular expressions embedded in /regex/ pattern nodes and executes them via re.search against tree node labels without any validation or timeout. An attacker who controls the tgrep pattern (e.g., via tgrep_positions() or tgrep_compile() exposed to external input) can supply a pattern that triggers catastrophic backtracking, causing indefinite CPU saturation that blocks the Python process.

CVSS v3
5.9
EG Score
5.9MEDIUMmedium confidence
EG Risk
43
EG Risk 43/100

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 (value × EchelonGraph’s weight)
Severity59% × 45%
The EG Score, 5.9 of 10.
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 or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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.
EPSS PROB
0.4%
EPSS %ILE
36th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (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 26, 2026

Last Modified

September 1, 2026

Advisory Details (2)

Auto-updated Aug 26, 2026
Patch available. Sources: github.
Web page

NLTK 3.10.2 Regular Expression Denial of Service via tgrep | Advisories | VulnCheck

https://www.vulncheck.com/advisories/nltk-3.10.2-regular-expression-denial-of-service-via-tgrep
GitHub advisoryMentions a patch (unverified)

ReDoS in nltk.tgrep via unvalidated user-supplied regular expressions · Advisory · nltk/nltk · GitHub

https://github.com/nltk/nltk/security/advisories/GHSA-w3v8-gmh9-3wv7

Vendor Advisories for CVE-2026-80206(1)

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

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
nltk3.10.0-1, 3.10.1-1, 3.9.1-2, 3.9.2-1, 3.9.3-1
  • every version up to 3.10.3-1: fixed in 3.10.3-1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
nltk0.8 ... 3.9b1 (68 versions)
  • every version up to 3.10.3: fixed in 3.10.3
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 52× 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.

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. 4 repeat rows among the latest 88 are merged into the row they repeat.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  3. 2026-10-12 14:57 UTCEG score recompute
  4. 2026-10-11 19:21 UTCEG score recompute
  5. 2026-10-11 16:37 UTCEG score recompute
  6. 2026-10-11 13:56 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  9. 2026-10-10 11:08 UTCEG score recompute
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  11. 2026-10-09 08:00 UTCEG score recompute
  12. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  13. 2026-10-08 05:55 UTCEG score recompute
  14. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  15. 2026-10-07 03:50 UTCEG score recompute
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  17. 2026-10-06 01:46 UTCEG score recompute
  18. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  19. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  20. 2026-10-03 16:12 UTCEG score recompute
  21. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  22. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  23. 2026-10-02 10:20 UTCEG score recompute
  24. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  25. 2026-10-01 08:15 UTCEG score recompute
Show 59 more
  1. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  2. 2026-09-30 06:10 UTCEG score recompute
  3. 2026-09-29 01:26 UTCEG score recompute
  4. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  5. 2026-09-27 23:15 UTCEG score recompute
  6. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  7. 2026-09-26 21:10 UTCEG score recompute
  8. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  9. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  10. 2026-09-24 19:51 UTCEG score recompute
  11. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  12. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  13. 2026-09-23 17:47 UTCEG score recompute
  14. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  15. 2026-09-22 15:15 UTCEG score recompute
  16. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  17. 2026-09-21 13:11 UTCEG score recompute
  18. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  19. 2026-09-20 11:07 UTCEG score recompute
  20. 2026-09-19 09:03 UTCEG score recompute
  21. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  22. 2026-09-18 06:58 UTCEG score recompute
  23. 2026-09-17 04:54 UTCEG score recompute
  24. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  25. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  26. 2026-09-16 02:49 UTCEG score recompute
  27. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  28. 2026-09-13 22:41 UTCEG score recompute
  29. 2026-09-12 20:37 UTCEG score recompute
  30. 2026-09-11 18:33 UTCEG score recompute
  31. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  32. 2026-09-10 16:28 UTCEG score recompute
  33. 2026-09-09 13:53 UTCEG score recompute
  34. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  35. 2026-09-08 11:27 UTCEG score recompute
  36. 2026-09-07 06:54 UTCEG score recompute
  37. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  38. 2026-09-06 04:44 UTCEG score recompute
  39. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  40. 2026-09-05 02:40 UTCEG score recompute
  41. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  42. 2026-09-02 22:25 UTCEG score recompute
  43. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  44. 2026-09-01 20:21 UTCEG score recompute
  45. 2026-09-01 20:21 UTCGHSA enrichmentGHSA-vf76-f5cp-9846 · GitHub severity HIGH · GitHub CVSS 5.9
  46. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  47. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  48. 2026-08-31 04:11 UTCEG score recompute
  49. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  50. 2026-08-30 02:03 UTCEG score recompute
  51. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  52. 2026-08-28 23:58 UTCEG score recompute
  53. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  54. 2026-08-27 18:07 UTCEG score recompute
  55. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  56. 2026-08-26 15:53 UTCEG score recompute
  57. 2026-08-26 12:58 UTCEG score recompute
  58. 2026-08-26 10:48 UTCEG score recomputeFirst assessed: 5.9 MEDIUM
  59. 2026-08-26 10:47 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-80206?
CVE-2026-80206 is a medium-severity vulnerability; its CVE record was published on August 26, 2026. NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep module. The tgrepnodeaction function compiles user-supplied regular expressions embedded in /regex/ pattern nodes and executes them via re.search against tree node labels without any validation or…
When was CVE-2026-80206 made public?
CVE-2026-80206 was made public on August 12, 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 26, 2026. EchelonGraph's copy of the record carries a last-modified date of September 1, 2026; the record at its source may have been updated since.
Is CVE-2026-80206 actively exploited?
CVE-2026-80206 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (36th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-80206?
CVE-2026-80206 has a CVSS base score of 5.9 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-80206?
A fix for CVE-2026-80206 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-80206 are linked in the Vendor Advisories panel on this page.

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