CVE-2026-81725

LOWPre-NVD 3.73.7
EchelonGraph scoreMEDIUM confidence

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

Score 3.7 from GitHub Security Advisory published 2026-08-27. A secondary CVSS source baseline 3.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
3.7EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 3.7Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

NLTK before 3.10.3 contains a regular expression denial of service vulnerability in Pl196xCorpusReader that allows attackers to cause quadratic CPU consumption by supplying malformed TEI blocks with many unmatched opening tags. Attackers can exploit lazy regex patterns in the read_block method through public APIs like words() and tagged_words() to force repeated rescans and achieve near-quadratic runtime growth.

CVSS v3
3.7
EG Score
3.7LOWmedium confidence
EG Risk
17
EG Risk 17/100

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)
Severity37% × 45%
The EG Score, 3.7 of 10.
Exploitation0.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (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
28th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

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

Exploitation none (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 27, 2026

Last Modified

September 1, 2026

References (2)

Vendor Advisories for CVE-2026-81725(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 12× in last 7d / 38× 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 68 are merged into the row they repeat.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  3. 2026-10-12 14:56 UTCEG score recompute
  4. 2026-10-11 19:20 UTCEG score recompute
  5. 2026-10-11 16:36 UTCEG score recompute
  6. 2026-10-11 13:54 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  10. 2026-10-09 07:20 UTCEG score recompute
  11. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  12. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  13. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  14. 2026-10-06 07:33 UTCEG score recompute
  15. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  16. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  17. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  18. 2026-10-03 04:51 UTCEG score recompute
  19. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  20. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  21. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  22. 2026-09-30 05:00 UTCEG score recompute
  23. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  24. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  25. 2026-09-26 18:43 UTCEG score recompute
Show 39 more
  1. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  2. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  3. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  4. 2026-09-22 19:20 UTCEG score recompute
  5. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  6. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  7. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  8. 2026-09-19 19:29 UTCEG score recompute
  9. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  10. 2026-09-16 19:43 UTCEG score recompute
  11. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  12. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  13. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-09-13 19:56 UTCEG score recompute
  15. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  16. 2026-09-10 20:09 UTCEG score recompute
  17. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  18. 2026-09-07 20:22 UTCEG score recompute
  19. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  20. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-09-04 20:35 UTCEG score recompute
  22. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  23. 2026-09-01 20:21 UTCEG score recompute
  24. 2026-09-01 20:20 UTCGHSA enrichmentGHSA-3m7f-6hxv-6796 · GitHub CVSS 3.7
  25. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  26. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  27. 2026-08-31 20:54 UTCGHSA enrichmentGHSA-3m7f-6hxv-6796 · GitHub CVSS 3.7
  28. 2026-08-31 20:48 UTCEG score recompute
  29. 2026-08-31 20:48 UTCGHSA enrichmentGHSA-3m7f-6hxv-6796 · GitHub CVSS 3.7
  30. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  31. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  32. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  33. 2026-08-28 20:43 UTCEG score recompute
  34. 2026-08-28 20:43 UTCGHSA enrichmentGHSA-3m7f-6hxv-6796 · GitHub CVSS 3.7
  35. 2026-08-28 19:47 UTCEG score recompute
  36. 2026-08-28 19:47 UTCGHSA enrichmentGHSA-3m7f-6hxv-6796 · GitHub CVSS 3.7
  37. 2026-08-27 17:24 UTCEG score recompute
  38. 2026-08-27 16:47 UTCEG score recomputeFirst assessed: 3.7 LOW
  39. 2026-08-27 16:43 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-81725?
CVE-2026-81725 is a low-severity vulnerability; its CVE record was published on August 27, 2026. NLTK before 3.10.3 contains a regular expression denial of service vulnerability in Pl196xCorpusReader that allows attackers to cause quadratic CPU consumption by supplying malformed TEI blocks with many unmatched opening tags. Attackers can exploit lazy regex patterns in the readblock method…
When was CVE-2026-81725 made public?
CVE-2026-81725 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 27, 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-2026-81725 actively exploited?
CVE-2026-81725 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (28th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-81725?
CVE-2026-81725 has a CVSS base score of 3.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-81725?
A fix for CVE-2026-81725 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-81725 are linked in the Vendor Advisories panel on this page.

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