CVE-2026-81888

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 96% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.4Exploit: None knownExposed: 0

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

@hono/oauth-providers is Authentication middleware for Hono. Prior to version 0.8.6, the built-in social login providers accept an OAuth callback even when the state value is absent on both sides, so the anti-CSRF check passes for a callback that never came from a genuine login attempt. This defeats the state-based CSRF protection under default usage. Version 0.8.6 has a patch.

CVSS v3
5.4
EG Score
5.4(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: 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
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
KEV
Not listed

Published

August 31, 2026

Last Modified

September 9, 2026

Advisory Details (3)

Auto-updated Aug 31, 2026
Patch available. Sources: github, github_pr, github_commit.
github_commit Patch Available

commit b37765f40b7b (honojs/middleware)

Patch available: honojs/middleware @hono/[email protected] (contains commit b37765f40b7b)

https://github.com/honojs/middleware/commit/b37765f40b7bddb1d8fce39573b085222dea58c1
github_pr Patch Available

fix(oauth-providers): fail closed on missing OAuth state to prevent login CSRF

Patch available: honojs/middleware @hono/[email protected] (PR #2040 merged 2026-07-15)

https://github.com/honojs/middleware/pull/2040
github Patch Available

OAuth state check fails open on omitted state in @hono/oauth-providers, enabling login CSRF and forced account linking · Advisory · honojs/middleware · GitHub

https://github.com/honojs/middleware/security/advisories/GHSA-fm3f-ch8h-qw8q

Vendor Advisories for CVE-2026-81888(1)

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

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
@hono/oauth-providers—0.8.6—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 32× 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 22:01 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 21:56 UTCEG score recompute
  4. 2026-09-16 21:51 UTCEG score recompute
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 05:15 UTCEPSS rescore
  7. 2026-09-15 21:45 UTCEG score recompute
  8. 2026-09-15 03:12 UTCEPSS rescore
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-13 21:35 UTCEG score recompute
  11. 2026-09-12 21:30 UTCEG score recompute
  12. 2026-09-11 21:24 UTCEG score recompute
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-10 21:16 UTCEG score recompute
  16. 2026-09-08 23:29 UTCEG score recompute
  17. 2026-09-08 22:01 UTCEPSS rescore
  18. 2026-09-07 16:26 UTCEG score recompute
  19. 2026-09-06 16:21 UTCEG score recompute
  20. 2026-09-06 13:48 UTCEPSS rescore
  21. 2026-09-05 16:15 UTCEG score recompute
  22. 2026-09-05 15:31 UTCEPSS rescore
  23. 2026-09-04 16:09 UTCEG score recompute
  24. 2026-09-04 05:07 UTCEPSS rescore
  25. 2026-09-02 15:54 UTCEG score recompute
Show 7 more
  1. 2026-09-02 14:12 UTCEPSS rescore
  2. 2026-09-01 15:42 UTCEG score recompute
  3. 2026-09-01 15:13 UTCEG score recompute
  4. 2026-09-01 13:54 UTCEPSS rescore
  5. 2026-08-31 21:22 UTCEG score recompute
  6. 2026-08-31 20:35 UTCEG score recompute
  7. 2026-08-31 20:34 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-81888?
CVE-2026-81888 is a medium vulnerability published on August 31, 2026. @hono/oauth-providers is Authentication middleware for Hono. Prior to version 0.8.6, the built-in social login providers accept an OAuth callback even when the state value is absent on both sides, so the anti-CSRF check passes for a callback that never came from a genuine login attempt. This…
When was CVE-2026-81888 disclosed?
CVE-2026-81888 was first published in the National Vulnerability Database on August 31, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81888 actively exploited?
CVE-2026-81888 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 95.5% of all scored CVEs.
What is the CVSS score of CVE-2026-81888?
CVE-2026-81888 has a CVSS v3 base score of 5.4 (NVD).
How do I remediate CVE-2026-81888?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81888, 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-2026-81888

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