CVE-2026-81727

HIGHPre-NVD 7.17.1
EchelonGraph scoreMEDIUM confidence

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

Score 7.1 from GitHub Security Advisory published 2026-08-27. A secondary CVSS source baseline 7.1; 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
7.1EG
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: 0.2%CVSS: 7.1Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incr_download methods that allows attackers to overwrite files outside the install root through pre-existing hardlinks. Attackers with write access to a shared downloader directory can create hardlinks pointing to outside-root files that are then overwritten during normal package extraction, mutating files outside the intended install tree.

CVSS v3
7.1
EG Score
7.1HIGHmedium confidence
EG Risk
48
EG Risk 48/100

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)
Severity71% × 45%
The EG Score, 7.1 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
0.2%
EPSS %ILE
7th
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 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 Hardlink File Overwrite via downloader | Advisories | VulnCheck

https://www.vulncheck.com/advisories/nltk-before-3.10.3-hardlink-file-overwrite-via-downloader
GitHub advisoryMentions a patch (unverified)

Downloader.download follows hardlinks and overwrites outside-root files · Advisory · nltk/nltk · GitHub

https://github.com/nltk/nltk/security/advisories/GHSA-f794-5jv7-7672

Vendor Advisories for CVE-2026-81727(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 20× in last 7d / 86× 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 98 of 129 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. 2 repeat rows among the latest 100 are merged into the row they repeat. The 31 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 0.2% · 7th percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  3. 2026-10-12 16:00 UTCEG score recompute
  4. 2026-10-12 16:00 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 0.2% · 7th percentile
  10. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  11. 2026-10-10 15:12 UTCVendor advisory
  12. 2026-10-10 01:53 UTCEG score recompute
  13. 2026-10-10 01:53 UTCVendor advisory
  14. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  15. 2026-10-09 03:04 UTCEG score recompute
  16. 2026-10-09 03:04 UTCVendor advisory
  17. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  18. 2026-10-08 01:19 UTCEG score recompute
  19. 2026-10-08 01:19 UTCVendor advisory
  20. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  21. 2026-10-07 09:26 UTCVendor advisory
  22. 2026-10-06 20:41 UTCEG score recompute
  23. 2026-10-06 20:41 UTCVendor advisory
  24. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  25. 2026-10-06 07:32 UTCVendor advisory
Show 73 more
  1. 2026-10-05 18:19 UTCEG score recompute
  2. 2026-10-05 18:19 UTCVendor advisory
  3. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  4. 2026-10-05 05:32 UTCEG score recompute
  5. 2026-10-05 05:32 UTCVendor advisory
  6. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  7. 2026-10-04 16:47 UTCVendor advisory
  8. 2026-10-04 04:01 UTCVendor advisory
  9. 2026-10-03 15:13 UTCEG score recompute
  10. 2026-10-03 15:13 UTCVendor advisory
  11. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  12. 2026-10-02 22:59 UTCEG score recompute
  13. 2026-10-02 22:59 UTCVendor advisory
  14. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  15. 2026-10-02 10:09 UTCVendor advisory
  16. 2026-10-01 21:24 UTCEG score recompute
  17. 2026-10-01 21:24 UTCVendor advisory
  18. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  19. 2026-10-01 08:39 UTCVendor advisory
  20. 2026-09-30 19:54 UTCEG score recompute
  21. 2026-09-30 19:54 UTCVendor advisory
  22. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  23. 2026-09-30 05:00 UTCEG score recompute
  24. 2026-09-30 05:00 UTCVendor advisory
  25. 2026-09-29 12:16 UTCVendor advisory
  26. 2026-09-28 21:50 UTCEG score recompute
  27. 2026-09-28 21:50 UTCVendor advisory
  28. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  29. 2026-09-28 09:05 UTCVendor advisory
  30. 2026-09-27 20:20 UTCEG score recompute
  31. 2026-09-27 20:20 UTCVendor advisory
  32. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  33. 2026-09-27 07:35 UTCVendor advisory
  34. 2026-09-26 18:43 UTCEG score recompute
  35. 2026-09-26 18:43 UTCVendor advisory
  36. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  37. 2026-09-25 16:03 UTCVendor advisory
  38. 2026-09-25 03:16 UTCVendor advisory
  39. 2026-09-24 14:31 UTCEG score recompute
  40. 2026-09-24 14:31 UTCVendor advisory
  41. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  42. 2026-09-24 01:37 UTCEG score recompute
  43. 2026-09-24 01:37 UTCVendor advisory
  44. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  45. 2026-09-23 12:53 UTCVendor advisory
  46. 2026-09-23 00:08 UTCEG score recompute
  47. 2026-09-23 00:08 UTCVendor advisory
  48. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  49. 2026-09-21 22:39 UTCEG score recompute
  50. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  51. 2026-09-20 21:08 UTCEG score recompute
  52. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  53. 2026-09-19 17:51 UTCEG score recompute
  54. 2026-09-19 05:06 UTCEG score recompute
  55. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  56. 2026-09-17 01:22 UTCEG score recompute
  57. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  58. 2026-09-16 12:37 UTCEG score recompute
  59. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  60. 2026-09-15 11:07 UTCEG score recompute
  61. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  62. 2026-09-13 20:29 UTCEG score recompute
  63. 2026-09-12 18:59 UTCEG score recompute
  64. 2026-09-11 17:29 UTCEG score recompute
  65. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  66. 2026-09-10 15:35 UTCEG score recompute
  67. 2026-09-09 00:40 UTCEG score recompute
  68. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  69. 2026-09-07 17:14 UTCEG score recompute
  70. 2026-09-06 15:43 UTCEG score recompute
  71. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  72. 2026-09-05 01:26 UTCEG score recompute
  73. 2026-09-04 12:41 UTCEG score recompute

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

Frequently asked(5)

What is CVE-2026-81727?
CVE-2026-81727 is a high-severity vulnerability; its CVE record was published on August 27, 2026. NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incr_download methods that allows attackers to overwrite files outside the install root through pre-existing hardlinks. Attackers with write access to a shared downloader…
When was CVE-2026-81727 made public?
CVE-2026-81727 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-2026-81727 actively exploited?
CVE-2026-81727 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (7th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-81727?
CVE-2026-81727 has a CVSS base score of 7.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-81727?
A fix for CVE-2026-81727 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-81727 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-2026-81727

Explore →

Is Your Infrastructure Affected by CVE-2026-81727?

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

Book a Demo →Browse All CVEs