CVE-2026-81722

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-27. A secondary CVSS source baseline 7.5; 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
7.5EG
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: 7.5Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

nltk PorterStemmer in versions <= 3.10.2 (fixed in 3.10.3) contains an inefficient-algorithmic-complexity denial of service in PorterStemmer.stem(). The _is_consonant() helper walks backward over the entire run of trailing 'y' characters on every call, and _measure() invokes it for each stem position, causing O(n^2) behavior. A single ~20-50 KB untrusted token consisting of a long run of the letter 'y' followed by a matching suffix (e.g., 'ness') can pin a CPU core for seconds to minutes, causing availability impact.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
65
EG Risk 65/100

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)
Severity75% × 45%
The EG Score, 7.5 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
42nd
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 PorterStemmer before 3.10.3 Quadratic-time DoS | Advisories | VulnCheck

https://www.vulncheck.com/advisories/nltk-porterstemmer-before-3.10.3-quadratic-time-dos
GitHub advisoryMentions a patch (unverified)

Quadratic-time DoS in PorterStemmer via long runs of 'y' · Advisory · nltk/nltk · GitHub

https://github.com/nltk/nltk/security/advisories/GHSA-ww6m-cw3f-q94g

Vendor Advisories for CVE-2026-81722(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 / 88× 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 132 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 34 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% · 42nd percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.5% · 42nd 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 0.5% · 42nd percentile
  10. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  11. 2026-10-10 14:24 UTCVendor advisory
  12. 2026-10-10 01:54 UTCEG score recompute
  13. 2026-10-10 01:54 UTCVendor advisory
  14. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  15. 2026-10-09 03:05 UTCEG score recompute
  16. 2026-10-09 03:05 UTCVendor advisory
  17. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 42nd 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 0.5% · 42nd percentile
  21. 2026-10-07 09:10 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 0.5% · 42nd percentile
  25. 2026-10-06 07:33 UTCEG score recompute
Show 73 more
  1. 2026-10-06 07:33 UTCVendor advisory
  2. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  3. 2026-10-05 17:09 UTCVendor advisory
  4. 2026-10-05 04:41 UTCEG score recompute
  5. 2026-10-05 04:41 UTCVendor advisory
  6. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  7. 2026-10-04 16:12 UTCVendor advisory
  8. 2026-10-04 03:41 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 0.5% · 42nd percentile
  12. 2026-10-02 21:54 UTCEG score recompute
  13. 2026-10-02 21:54 UTCVendor advisory
  14. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  15. 2026-10-02 09:25 UTCVendor advisory
  16. 2026-10-01 20:57 UTCEG score recompute
  17. 2026-10-01 20:57 UTCVendor advisory
  18. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  19. 2026-10-01 08:24 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 0.5% · 42nd percentile
  23. 2026-09-30 05:00 UTCEG score recompute
  24. 2026-09-30 05:00 UTCVendor advisory
  25. 2026-09-29 12:16 UTCEG score recompute
  26. 2026-09-29 12:16 UTCVendor advisory
  27. 2026-09-28 21:15 UTCEG score recompute
  28. 2026-09-28 21:15 UTCVendor advisory
  29. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  30. 2026-09-28 08:10 UTCVendor advisory
  31. 2026-09-27 19:41 UTCEG score recompute
  32. 2026-09-27 19:41 UTCVendor advisory
  33. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  34. 2026-09-27 07:12 UTCVendor advisory
  35. 2026-09-26 18:43 UTCEG score recompute
  36. 2026-09-26 18:43 UTCVendor advisory
  37. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  38. 2026-09-25 07:15 UTCVendor advisory
  39. 2026-09-24 18:46 UTCEG score recompute
  40. 2026-09-24 18:46 UTCVendor advisory
  41. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  42. 2026-09-24 06:11 UTCEG score recompute
  43. 2026-09-24 06:11 UTCVendor advisory
  44. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  45. 2026-09-23 17:43 UTCVendor advisory
  46. 2026-09-23 05:06 UTCVendor advisory
  47. 2026-09-22 16:37 UTCEG score recompute
  48. 2026-09-22 16:37 UTCVendor advisory
  49. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  50. 2026-09-22 03:55 UTCEG score recompute
  51. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  52. 2026-09-21 02:57 UTCEG score recompute
  53. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  54. 2026-09-20 01:57 UTCEG score recompute
  55. 2026-09-19 00:59 UTCEG score recompute
  56. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  57. 2026-09-18 00:03 UTCEG score recompute
  58. 2026-09-16 21:44 UTCEG score recompute
  59. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  60. 2026-09-16 09:15 UTCEG score recompute
  61. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  62. 2026-09-15 07:17 UTCEG score recompute
  63. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  64. 2026-09-13 17:04 UTCEG score recompute
  65. 2026-09-12 16:06 UTCEG score recompute
  66. 2026-09-11 15:10 UTCEG score recompute
  67. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  68. 2026-09-10 14:11 UTCEG score recompute
  69. 2026-09-09 00:40 UTCEG score recompute
  70. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  71. 2026-09-08 03:35 UTCEG score recompute
  72. 2026-09-07 01:27 UTCEG score recompute
  73. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.4% · 29th percentile

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

Frequently asked(5)

What is CVE-2026-81722?
CVE-2026-81722 is a high-severity vulnerability; its CVE record was published on August 27, 2026. nltk PorterStemmer in versions <= 3.10.2 (fixed in 3.10.3) contains an inefficient-algorithmic-complexity denial of service in PorterStemmer.stem(). The isconsonant() helper walks backward over the entire run of trailing 'y' characters on every call, and _measure() invokes it for each stem…
When was CVE-2026-81722 made public?
CVE-2026-81722 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-2026-81722 actively exploited?
CVE-2026-81722 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (42nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-81722?
CVE-2026-81722 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-81722?
A fix for CVE-2026-81722 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-81722 are linked in the Vendor Advisories panel on this page.

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