CVE-2026-71403

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 91% 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, nvd
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.1Exploit: None knownExposed: 0

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

A flaw was found in Rancher Manager. The /v3/users update path did not enforce immutability of a User resource's username and principalIds fields. A user holding the update verb on users.management.cattle.io could inject a foreign identity provider principal into any account, so that the next login by the owner of that principal was bound to the victim's account and inherited its role bindings.

This issue affects Rancher: before 2.15.1.

CVSS v3
6.1
EG Score
6.1(medium)
EG Risk
28(Track)
EG Risk 28/100SSVC: 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
Severity61% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

September 3, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Sep 3, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
github_pr

[v2.15] Fix User principalIds

Fix merged in rancher/rancher PR #56616 on 2026-08-14 — awaiting tagged release

https://github.com/rancher/rancher/pull/56616

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× 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.

  1. 2026-09-20 20:16 UTCEPSS rescore
  2. 2026-09-20 15:01 UTCEG score recompute
  3. 2026-09-19 15:14 UTCEG score recompute
  4. 2026-09-18 19:28 UTCEPSS rescore
  5. 2026-09-18 15:27 UTCEG score recompute
  6. 2026-09-17 22:19 UTCEG score recompute
  7. 2026-09-16 22:32 UTCEG score recompute
  8. 2026-09-16 14:08 UTCEPSS rescore
  9. 2026-09-16 05:15 UTCEPSS rescore
  10. 2026-09-15 22:25 UTCEG score recompute
  11. 2026-09-15 03:12 UTCEPSS rescore
  12. 2026-09-13 22:49 UTCEG score recompute
  13. 2026-09-12 23:03 UTCEG score recompute
  14. 2026-09-12 15:02 UTCEPSS rescore
  15. 2026-09-11 23:16 UTCEG score recompute
  16. 2026-09-11 14:53 UTCEPSS rescore
  17. 2026-09-10 23:15 UTCEG score recompute
  18. 2026-09-10 09:35 UTCEPSS rescore
  19. 2026-09-09 23:28 UTCEG score recompute
  20. 2026-09-08 22:01 UTCEPSS rescore
  21. 2026-09-08 03:34 UTCEG score recompute
  22. 2026-09-07 03:46 UTCEG score recompute
  23. 2026-09-06 13:48 UTCEPSS rescore
  24. 2026-09-06 03:58 UTCEG score recompute
  25. 2026-09-05 04:11 UTCEG score recompute
Show 5 more
  1. 2026-09-04 04:23 UTCEG score recompute
  2. 2026-09-04 04:07 UTCEG score recompute
  3. 2026-09-03 15:31 UTCEG score recompute
  4. 2026-09-03 14:51 UTCEG score recompute
  5. 2026-09-03 14:48 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-71403?
CVE-2026-71403 is a medium vulnerability published on September 3, 2026. A flaw was found in Rancher Manager. The /v3/users update path did not enforce immutability of a User resource's username and principalIds fields. A user holding the update verb on users.management.cattle.io could inject a foreign identity provider principal into any account, so that the next login…
When was CVE-2026-71403 disclosed?
CVE-2026-71403 was first published in the National Vulnerability Database on September 3, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-71403 actively exploited?
CVE-2026-71403 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 91.3% of all scored CVEs.
What is the CVSS score of CVE-2026-71403?
CVE-2026-71403 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-71403?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-71403, 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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