CVE-2026-81723

LOWPre-NVD 3.73.7—
EchelonGraph scoreHIGH confidence

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, ghsa, secondary
Elevated
3.7EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 3.7Exploit: Elevated riskExposed: 0

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

NLTK versions before 3.10.3 contain a quadratic CPU exhaustion vulnerability in XMLCorpusView._read_xml_fragment() that rescans accumulated XML fragments on every 1 KiB block read. Attackers can provide malformed XML corpus files to cause severe CPU consumption and denial of service through affected readers like BNCCorpusReader.

CVSS v3
3.7
EG Score
3.7(high)
EG Risk
33(Track)
EG Risk 33/100SSVC: Track

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
Severity37% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
13%
KEV
Not listed

Published

August 27, 2026

Last Modified

August 31, 2026

References (3)

Vendor Advisories for CVE-2026-81723(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 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
nltk3.10.0-1, 3.10.1-1, 3.9.1-2, 3.9.2-1, 3.9.3-13.10.3-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
nltk0.8 ... 3.9b1 (68 versions)3.10.3—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 33× 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 19:28 UTCEPSS rescore
  2. 2026-09-16 14:08 UTCEPSS rescore
  3. 2026-09-16 06:34 UTCEG score recompute
  4. 2026-09-16 05:15 UTCEPSS rescore
  5. 2026-09-15 03:12 UTCEPSS rescore
  6. 2026-09-15 03:12 UTCEPSS rescore
  7. 2026-09-13 04:30 UTCEG score recompute
  8. 2026-09-11 14:53 UTCEPSS rescore
  9. 2026-09-11 14:53 UTCEPSS rescore
  10. 2026-09-10 02:25 UTCEG score recompute
  11. 2026-09-08 22:01 UTCEPSS rescore
  12. 2026-09-07 00:21 UTCEG score recompute
  13. 2026-09-06 13:48 UTCEPSS rescore
  14. 2026-09-05 15:31 UTCEPSS rescore
  15. 2026-09-04 05:07 UTCEPSS rescore
  16. 2026-09-03 22:12 UTCEG score recompute
  17. 2026-09-02 14:12 UTCEPSS rescore
  18. 2026-09-01 13:54 UTCEPSS rescore
  19. 2026-09-01 04:40 UTCEPSS rescore
  20. 2026-09-01 04:40 UTCEPSS rescore
  21. 2026-08-31 19:33 UTCEG score recompute
  22. 2026-08-31 19:33 UTCGHSA enrichment
  23. 2026-08-31 18:35 UTCEG score recompute
  24. 2026-08-31 18:34 UTCGHSA enrichment
  25. 2026-08-30 19:28 UTCEG score recompute
Show 8 more
  1. 2026-08-30 19:28 UTCGHSA enrichment
  2. 2026-08-30 19:18 UTCEPSS rescore
  3. 2026-08-30 19:17 UTCEPSS rescore
  4. 2026-08-30 01:22 UTCEPSS rescore
  5. 2026-08-28 21:42 UTCEPSS rescore
  6. 2026-08-27 17:24 UTCEG score recompute
  7. 2026-08-27 16:47 UTCEG score recompute
  8. 2026-08-27 16:43 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-81723?
CVE-2026-81723 is a low vulnerability published on August 27, 2026. NLTK versions before 3.10.3 contain a quadratic CPU exhaustion vulnerability in XMLCorpusView.readxml_fragment() that rescans accumulated XML fragments on every 1 KiB block read. Attackers can provide malformed XML corpus files to cause severe CPU consumption and denial of service through affected…
When was CVE-2026-81723 disclosed?
CVE-2026-81723 was first published in the National Vulnerability Database on August 27, 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-2026-81723 actively exploited?
CVE-2026-81723 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 87.0% of all scored CVEs.
What is the CVSS score of CVE-2026-81723?
CVE-2026-81723 has a CVSS v3 base score of 3.7 (NVD).
How do I remediate CVE-2026-81723?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81723, 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-2026-81723

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