CVE-2026-75866

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

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

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-22. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory
Trending — 3 sources updated this week

Also known asEUVD-2026-64293 (ENISA EUVD) · GHSA-cjjx-w599-qf62 (GitHub Security Advisories)Source: ENISA EUVD

9.1EG
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).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.1Exploit: None knownExposed services: Not assessed

Upgrade to Punk-OAuth2 0.04 or later (from the CVE record's solution, CPAN Security Group) — apply it.

Punk::OAuth2::Server versions through 0.03 for Perl issue access tokens outside a client's registered scopes and grant types because no authorization path reads them.

Punk::OAuth2::Server::Store registers scopes and grant_types per client and documents both as client registration. token dispatches on the grant_type in the request body, so a client registered for authorization_code alone can ask for client_credentials, and that arm passes the requested scope straight to the minter, which signs it into the at+jwt access token. authorize copies the query scope into the authorization code record without comparing it against the registration, leaving the optional consent hook as the only check between an arbitrary scope and the issued code. redirect_uris on the same client row is read and enforced.

A registered client can obtain a correctly signed token carrying any scope it names, and a resource server running Punk::OAuth2::Checker accepts that token and honours the scope. A client registered without a secret authenticates on its client_id alone, so anyone who knows that identifier can request one.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
56
EG Risk 56/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
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 none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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: Upgrade to Punk-OAuth2 0.04 or later (from the CVE record's solution, CPAN Security Group). 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

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-30). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

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

Upgrade to Punk-OAuth2 0.04 or later (from the CVE record's solution, CPAN Security Group). Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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)3 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 total (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 22, 2026

Last Modified

October 15, 2026

Advisory Details (5)

Auto-updated Sep 15, 2026
Fix named in the CVE record's solution (CPAN Security Group).
Web page

oss-security - CVE-2026-75866: Punk::OAuth2::Server versions through 0.03 for Perl issue access tokens outside a client's registered scopes and grant types because no authorization path reads them

http://www.openwall.com/lists/oss-security/2026/08/22/6
Web page

RFC 6749 - The OAuth 2.0 Authorization Framework

https://datatracker.ietf.org/doc/html/rfc6749#section-5.2
Web page

RFC 6749 - The OAuth 2.0 Authorization Framework

https://datatracker.ietf.org/doc/html/rfc6749#section-3.3

Vendor Advisories for CVE-2026-75866(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 116× 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 100 of 377 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. None are among the latest 100 rows. The 277 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-31 05:03 UTCEG score recompute
  2. 2026-10-31 05:03 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  3. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  4. 2026-10-30 04:57 UTCEG score recompute
  5. 2026-10-30 04:57 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  6. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  7. 2026-10-29 04:52 UTCEG score recompute
  8. 2026-10-29 04:52 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  9. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  10. 2026-10-28 04:48 UTCEG score recompute
  11. 2026-10-28 04:48 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  12. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  13. 2026-10-27 04:43 UTCEG score recompute
  14. 2026-10-27 04:43 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  15. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  16. 2026-10-26 00:12 UTCEG score recompute
  17. 2026-10-26 00:12 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  18. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  19. 2026-10-25 14:02 UTCEG score recompute
  20. 2026-10-25 00:07 UTCEG score recompute
  21. 2026-10-25 00:07 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  22. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  23. 2026-10-24 00:02 UTCEG score recompute
  24. 2026-10-24 00:02 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  25. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
Show 75 more
  1. 2026-10-22 23:56 UTCEG score recompute
  2. 2026-10-22 23:56 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  3. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  4. 2026-10-21 23:47 UTCEG score recompute
  5. 2026-10-21 23:47 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  6. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  7. 2026-10-20 23:42 UTCEG score recompute
  8. 2026-10-20 23:41 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  9. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  10. 2026-10-19 23:32 UTCEG score recompute
  11. 2026-10-19 23:32 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  12. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  13. 2026-10-18 22:56 UTCEG score recompute
  14. 2026-10-18 22:55 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  15. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  16. 2026-10-18 03:13 UTCEG score recompute
  17. 2026-10-17 22:49 UTCEG score recompute
  18. 2026-10-17 22:49 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  19. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  20. 2026-10-16 22:44 UTCEG score recompute
  21. 2026-10-16 22:44 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  22. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  23. 2026-10-15 19:27 UTCEG score recompute
  24. 2026-10-15 19:27 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  25. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  26. 2026-10-15 14:17 UTCEG score recompute
  27. 2026-10-15 14:16 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  28. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  29. 2026-10-14 09:00 UTCEG score recompute
  30. 2026-10-14 09:00 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  31. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  32. 2026-10-13 05:40 UTCEG score recompute
  33. 2026-10-13 05:40 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  34. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  35. 2026-10-12 15:39 UTCEG score recompute
  36. 2026-10-12 05:34 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  37. 2026-10-11 19:24 UTCEG score recompute
  38. 2026-10-11 16:40 UTCEG score recompute
  39. 2026-10-11 13:59 UTCEG score recompute
  40. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  41. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  42. 2026-10-10 16:36 UTCEG score recompute
  43. 2026-10-10 16:35 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  44. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  45. 2026-10-09 05:34 UTCEG score recompute
  46. 2026-10-09 05:34 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  47. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  48. 2026-10-08 09:02 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  49. 2026-10-08 04:44 UTCEG score recompute
  50. 2026-10-08 04:43 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  51. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  52. 2026-10-07 10:25 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  53. 2026-10-07 05:58 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  54. 2026-10-07 01:37 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  55. 2026-10-06 21:17 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  56. 2026-10-06 16:48 UTCEG score recompute
  57. 2026-10-06 16:48 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  58. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  59. 2026-10-06 12:11 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  60. 2026-10-06 07:48 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  61. 2026-10-06 03:01 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  62. 2026-10-05 18:56 UTCEG score recompute
  63. 2026-10-05 18:56 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  64. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  65. 2026-10-05 14:32 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  66. 2026-10-05 10:12 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  67. 2026-10-05 05:52 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  68. 2026-10-05 01:31 UTCEG score recompute
  69. 2026-10-05 01:31 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  70. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  71. 2026-10-04 20:47 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  72. 2026-10-04 15:38 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  73. 2026-10-04 11:10 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  74. 2026-10-04 06:42 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1
  75. 2026-10-04 02:23 UTCGHSA enrichmentGHSA-cjjx-w599-qf62 · GitHub severity CRITICAL · GitHub CVSS 9.1

Frequently asked(5)

What is CVE-2026-75866?
CVE-2026-75866 is a critical-severity vulnerability; its CVE record was published on August 22, 2026. Punk::OAuth2::Server versions through 0.03 for Perl issue access tokens outside a client's registered scopes and grant types because no authorization path reads them. Punk::OAuth2::Server::Store registers scopes and granttypes per client and documents both as client registration. token dispatches…
When was the CVE record for CVE-2026-75866 published?
The CVE record for CVE-2026-75866 was published on August 22, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 15, 2026; the record at its source may have been updated since.
Is CVE-2026-75866 actively exploited?
CVE-2026-75866 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-2026-75866?
CVE-2026-75866 has a CVSS v3.1 base score of 9.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-75866?
The CVE record's solution for CVE-2026-75866, written by its CNA CPAN Security Group, names the fix: "Upgrade to Punk-OAuth2 0.04 or later." The vendor advisories EchelonGraph has for CVE-2026-75866 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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