CVE-2026-81724

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

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

Score 5.3 from GitHub Security Advisory published 2026-08-27. A secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this weekElevated
5.3EG
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: 5.3Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

NLTK before 3.10.3 contains an uncontrolled recursion vulnerability in nltk.featstruct.FeatStructReader that allows unauthenticated attackers to cause a denial of service by supplying deeply nested feature-structure input. Attackers can craft trivial payloads with nested brackets that exceed Python's recursion limit and raise an unhandled RecursionError, crashing applications that parse user-supplied feature structures or feature grammars.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
55
EG Risk 55/100

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)
Severity53% × 45%
The EG Score, 5.3 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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 at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
37th
KEV
Not listed

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

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 yes (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)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

August 31, 2026

Advisory Details (2)

Auto-updated Aug 27, 2026
Patch available. Sources: github.
Web page

NLTK before 3.10.3 Denial of Service via Uncontrolled Recursion | Advisories | VulnCheck

https://www.vulncheck.com/advisories/nltk-before-3.10.3-denial-of-service-via-uncontrolled-recursion
GitHub advisoryMentions a patch (unverified)

Uncontrolled recursion in nltk.featstruct.FeatStructReader causes unhandled RecursionError (DoS) via deeply nested feature-structure input · Advisory · nltk/nltk · GitHub

https://github.com/nltk/nltk/security/advisories/GHSA-cw6x-m8jw-qmrh

Vendor Advisories for CVE-2026-81724(3)

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-llama-stack-core-rhel9:17891212862026-09-30redhat
redhatrhoai/odh-ta-lmes-job-rhel9:17889358632026-09-21redhat

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
nltk3.10.0-1, 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 19× in last 7d / 72× 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 96 of 108 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. 4 repeat rows among the latest 100 are merged into the row they repeat. The 12 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  3. 2026-10-12 16:14 UTCEG score recompute
  4. 2026-10-12 16:14 UTCVendor advisory
  5. 2026-10-12 14:56 UTCEG score recompute
  6. 2026-10-11 19:20 UTCEG score recompute
  7. 2026-10-11 16:36 UTCEG score recompute
  8. 2026-10-11 13:54 UTCEG score recompute
  9. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  10. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  11. 2026-10-10 05:46 UTCEG score recompute
  12. 2026-10-10 05:46 UTCVendor advisory
  13. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  14. 2026-10-09 06:06 UTCEG score recompute
  15. 2026-10-09 06:06 UTCVendor advisory
  16. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  17. 2026-10-08 06:37 UTCEG score recompute
  18. 2026-10-08 06:37 UTCVendor advisory
  19. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  20. 2026-10-07 07:07 UTCEG score recompute
  21. 2026-10-07 07:07 UTCVendor advisory
  22. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  23. 2026-10-06 07:33 UTCEG score recompute
  24. 2026-10-06 07:33 UTCVendor advisory
  25. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 37th percentile
Show 71 more
  1. 2026-10-05 05:03 UTCEG score recompute
  2. 2026-10-05 05:03 UTCVendor advisory
  3. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  4. 2026-10-04 05:33 UTCEG score recompute
  5. 2026-10-04 05:33 UTCVendor advisory
  6. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  7. 2026-10-03 06:03 UTCEG score recompute
  8. 2026-10-03 06:03 UTCVendor advisory
  9. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  10. 2026-10-02 06:19 UTCEG score recompute
  11. 2026-10-02 06:19 UTCVendor advisory
  12. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  13. 2026-10-01 04:31 UTCEG score recompute
  14. 2026-10-01 04:31 UTCVendor advisory
  15. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  16. 2026-09-30 05:00 UTCEG score recompute
  17. 2026-09-30 05:00 UTCVendor advisory
  18. 2026-09-28 21:15 UTCEG score recompute
  19. 2026-09-28 21:15 UTCVendor advisory
  20. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  21. 2026-09-27 18:12 UTCEG score recompute
  22. 2026-09-27 18:12 UTCVendor advisory
  23. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  24. 2026-09-26 18:43 UTCEG score recompute
  25. 2026-09-26 18:43 UTCVendor advisory
  26. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  27. 2026-09-24 19:23 UTCEG score recompute
  28. 2026-09-24 19:23 UTCVendor advisory
  29. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 36th percentile
  30. 2026-09-23 19:54 UTCEG score recompute
  31. 2026-09-23 19:54 UTCVendor advisory
  32. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  33. 2026-09-22 19:28 UTCEG score recompute
  34. 2026-09-22 19:28 UTCVendor advisory
  35. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  36. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  37. 2026-09-20 20:29 UTCEG score recompute
  38. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  39. 2026-09-19 20:59 UTCEG score recompute
  40. 2026-09-18 21:29 UTCEG score recompute
  41. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  42. 2026-09-17 21:00 UTCEG score recompute
  43. 2026-09-16 21:30 UTCEG score recompute
  44. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  45. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  46. 2026-09-15 21:35 UTCEG score recompute
  47. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  48. 2026-09-13 22:30 UTCEG score recompute
  49. 2026-09-12 23:01 UTCEG score recompute
  50. 2026-09-11 23:31 UTCEG score recompute
  51. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  52. 2026-09-11 00:01 UTCEG score recompute
  53. 2026-09-09 00:40 UTCEG score recompute
  54. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  55. 2026-09-07 17:58 UTCEG score recompute
  56. 2026-09-06 18:29 UTCEG score recompute
  57. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  58. 2026-09-05 19:00 UTCEG score recompute
  59. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  60. 2026-09-04 19:30 UTCEG score recompute
  61. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  62. 2026-09-02 20:29 UTCEG score recompute
  63. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  64. 2026-09-01 18:47 UTCEG score recompute
  65. 2026-09-01 18:46 UTCGHSA enrichmentGHSA-pf76-q698-37v8 · GitHub CVSS 5.3
  66. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  67. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  68. 2026-08-31 19:14 UTCGHSA enrichmentGHSA-pf76-q698-37v8 · GitHub CVSS 5.3
  69. 2026-08-31 17:35 UTCEG score recompute
  70. 2026-08-31 17:34 UTCGHSA enrichmentGHSA-pf76-q698-37v8 · GitHub CVSS 5.3
  71. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 17th percentile

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

Frequently asked(5)

What is CVE-2026-81724?
CVE-2026-81724 is a medium-severity vulnerability; its CVE record was published on August 27, 2026. NLTK before 3.10.3 contains an uncontrolled recursion vulnerability in nltk.featstruct.FeatStructReader that allows unauthenticated attackers to cause a denial of service by supplying deeply nested feature-structure input. Attackers can craft trivial payloads with nested brackets that exceed…
When was CVE-2026-81724 made public?
CVE-2026-81724 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 August 31, 2026; the record at its source may have been updated since.
Is CVE-2026-81724 actively exploited?
CVE-2026-81724 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (37th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-81724?
CVE-2026-81724 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-81724?
A fix for CVE-2026-81724 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-81724 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-81724

Explore →

Is Your Infrastructure Affected by CVE-2026-81724?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs