CVE-2026-45156

HIGHPre-NVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 65% 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
Trending — 3 sources updated this weekElevated
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.1Exploit: Elevated riskExposed: 0

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

Nextcloud is an open source content collaboration platform. From versions 0.3.0 to before 3.1.0, 5.0.0 to before 5.1.0, and 6.0.0 to before 6.4.0, a missing signature verification in User OIDC allowed a malicious ID4me authority to identify as any user. This issue has been patched in versions 3.1.0, 4.1.0, 5.1.0, 6.4.0 and 8.3.0.

CVSS v3
8.1
EG Score
8.1(medium)
EG Risk
52(Track)
EG Risk 52/100SSVC: 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
Severity81% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

June 1, 2026

Last Modified

July 22, 2026

Advisory Details (2)

Auto-updated Jun 3, 2026
Patch available. Sources: github, github_pr.
github_pr

Validate signature of id4me login tokens

Fix merged in nextcloud/user_oidc PR #1285 on 2026-01-12 — awaiting tagged release

https://github.com/nextcloud/user_oidc/pull/1285
github Patch Available

Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC · Advisory · nextcloud/security-advisories · GitHub

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 30× 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.

Showing the most recent 100 of 137 total refreshes for this CVE.

  1. 2026-09-16 05:15 UTCEPSS rescore
  2. 2026-09-14 06:09 UTCEG score recompute
  3. 2026-09-13 16:47 UTCEPSS rescore
  4. 2026-09-13 00:36 UTCOSV refresh
  5. 2026-09-12 15:01 UTCEPSS rescore
  6. 2026-09-11 14:53 UTCEPSS rescore
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  11. 2026-09-06 13:47 UTCEPSS rescore
  12. 2026-09-04 05:06 UTCEPSS rescore
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  15. 2026-08-30 19:17 UTCEPSS rescore
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  21. 2026-08-25 03:54 UTCEG score recompute
  22. 2026-08-23 13:54 UTCEG score recompute
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  24. 2026-08-21 23:49 UTCEPSS rescore
  25. 2026-08-21 14:52 UTCEG score recompute
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  1. 2026-08-20 22:55 UTCEPSS rescore
  2. 2026-08-20 10:18 UTCEG score recompute
  3. 2026-08-19 17:04 UTCEPSS rescore
  4. 2026-08-18 13:48 UTCEPSS rescore
  5. 2026-08-17 13:47 UTCEPSS rescore
  6. 2026-08-16 15:01 UTCEG score recompute
  7. 2026-08-16 14:56 UTCEPSS rescore
  8. 2026-08-16 02:59 UTCEG score recompute
  9. 2026-08-16 02:14 UTCEPSS rescore
  10. 2026-08-15 15:37 UTCEG score recompute
  11. 2026-08-15 01:30 UTCEPSS rescore
  12. 2026-08-13 23:21 UTCEG score recompute
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  17. 2026-08-11 01:49 UTCEG score recompute
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  19. 2026-08-09 15:43 UTCEG score recompute
  20. 2026-08-09 13:46 UTCEPSS rescore
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  22. 2026-08-08 16:37 UTCEPSS rescore
  23. 2026-08-07 18:08 UTCEG score recompute
  24. 2026-08-06 19:23 UTCEG score recompute
  25. 2026-08-06 13:46 UTCEPSS rescore
  26. 2026-08-05 20:39 UTCEG score recompute
  27. 2026-08-05 19:17 UTCEPSS rescore
  28. 2026-08-04 22:40 UTCEG score recompute
  29. 2026-08-04 15:10 UTCEPSS rescore
  30. 2026-08-04 10:38 UTCEPSS rescore
  31. 2026-08-03 15:50 UTCEG score recompute
  32. 2026-08-03 10:36 UTCEPSS rescore
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  36. 2026-08-01 04:16 UTCEPSS rescore
  37. 2026-07-31 05:43 UTCEG score recompute
  38. 2026-07-30 16:28 UTCEPSS rescore
  39. 2026-07-30 01:30 UTCEPSS rescore
  40. 2026-07-29 11:13 UTCEG score recompute
  41. 2026-07-28 15:36 UTCEPSS rescore
  42. 2026-07-28 03:52 UTCEG score recompute
  43. 2026-07-27 14:13 UTCEPSS rescore
  44. 2026-07-26 23:40 UTCEG score recompute
  45. 2026-07-26 14:54 UTCEPSS rescore
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  47. 2026-07-25 14:18 UTCEPSS rescore
  48. 2026-07-24 14:17 UTCEPSS rescore
  49. 2026-07-23 14:18 UTCEPSS rescore
  50. 2026-07-23 03:16 UTCEG score recompute
  51. 2026-07-22 14:08 UTCEPSS rescore
  52. 2026-07-21 15:24 UTCEPSS rescore
  53. 2026-07-20 17:08 UTCEPSS rescore
  54. 2026-07-19 14:31 UTCEPSS rescore
  55. 2026-07-19 02:29 UTCEPSS rescore
  56. 2026-07-18 10:04 UTCEPSS rescore
  57. 2026-07-16 17:03 UTCEPSS rescore
  58. 2026-07-15 16:57 UTCEPSS rescore
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  60. 2026-07-13 22:30 UTCEPSS rescore
  61. 2026-07-13 06:13 UTCEPSS rescore
  62. 2026-07-12 05:46 UTCEPSS rescore
  63. 2026-07-11 08:27 UTCEPSS rescore
  64. 2026-07-09 19:10 UTCEPSS rescore
  65. 2026-07-08 15:16 UTCEPSS rescore
  66. 2026-07-07 13:46 UTCEPSS rescore
  67. 2026-07-06 16:27 UTCEPSS rescore
  68. 2026-07-06 02:23 UTCEPSS rescore
  69. 2026-07-05 02:30 UTCEPSS rescore
  70. 2026-07-04 06:31 UTCEPSS rescore
  71. 2026-07-01 15:07 UTCEPSS rescore
  72. 2026-06-30 23:22 UTCEPSS rescore
  73. 2026-06-29 14:06 UTCEPSS rescore
  74. 2026-06-29 14:06 UTCEPSS rescore
  75. 2026-06-28 14:07 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCcybertechajju/CVE-2026-45156-POC
    First seen Jun 23, 2026

    This repository contains the Proof of Concept (PoC) exploit script for CVE-2026-45156

    Open source ↗

Frequently asked(5)

What is CVE-2026-45156?
CVE-2026-45156 is a high vulnerability published on June 1, 2026. Nextcloud is an open source content collaboration platform. From versions 0.3.0 to before 3.1.0, 5.0.0 to before 5.1.0, and 6.0.0 to before 6.4.0, a missing signature verification in User OIDC allowed a malicious ID4me authority to identify as any user. This issue has been patched in versions…
When was CVE-2026-45156 disclosed?
CVE-2026-45156 was first published in the National Vulnerability Database on June 1, 2026, with the most recent update on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45156 actively exploited?
CVE-2026-45156 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 65.3% of all scored CVEs.
What is the CVSS score of CVE-2026-45156?
CVE-2026-45156 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-45156?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45156, 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.

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