CVE-2026-91983

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreHIGH confidence

Score 4.3 from GitHub Security Advisory published 2026-09-15. a secondary CVSS source baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: Elevated riskExposed: 0

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

Vikunja before 2.6.0 contains an API token scope bypass vulnerability in task read endpoints where authorization fails to inspect query string parameters. Attackers with limited token scopes can use the expand parameter to access restricted data like comments, reactions, and time entries without proper permission verification.

CVSS v3
4.3
EG Score
4.3(high)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity43% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
21%
KEV
Not listed

Published

September 15, 2026

Last Modified

September 16, 2026

Advisory Details (2)

Auto-updated Sep 15, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

Vikunja before 2.6.0 API Token Scope Bypass via expand Parameter | Advisories | VulnCheck

https://www.vulncheck.com/advisories/vikunja-before-2.6.0-api-token-scope-bypass-via-expand-parameter
github Patch Available🟡 PoC Available

API token scopes bypassed via task expand parameter (comments, reactions, time entry counts) · Advisory · go-vikunja/vikunja · GitHub

https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9rg3-v78m-26q8

Vendor Advisories for CVE-2026-91983(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 20× in last 7d / 31× 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. 2026-09-25 00:20 UTCEG score recompute
  2. 2026-09-25 00:20 UTCGHSA enrichment
  3. 2026-09-24 14:04 UTCEPSS rescore
  4. 2026-09-23 23:56 UTCEG score recompute
  5. 2026-09-23 23:56 UTCGHSA enrichment
  6. 2026-09-23 17:54 UTCEPSS rescore
  7. 2026-09-22 23:34 UTCEG score recompute
  8. 2026-09-22 23:34 UTCGHSA enrichment
  9. 2026-09-22 16:01 UTCEPSS rescore
  10. 2026-09-21 23:02 UTCEG score recompute
  11. 2026-09-21 23:02 UTCGHSA enrichment
  12. 2026-09-21 21:09 UTCEPSS rescore
  13. 2026-09-20 22:39 UTCEG score recompute
  14. 2026-09-20 22:39 UTCGHSA enrichment
  15. 2026-09-20 20:16 UTCEPSS rescore
  16. 2026-09-19 22:16 UTCEG score recompute
  17. 2026-09-19 22:16 UTCGHSA enrichment
  18. 2026-09-18 21:52 UTCEG score recompute
  19. 2026-09-18 21:52 UTCGHSA enrichment
  20. 2026-09-18 19:28 UTCEPSS rescore
  21. 2026-09-17 21:30 UTCEG score recompute
  22. 2026-09-17 21:30 UTCGHSA enrichment
  23. 2026-09-17 19:32 UTCEPSS rescore
  24. 2026-09-16 21:07 UTCGHSA enrichment
  25. 2026-09-16 17:55 UTCEG score recompute
Show 6 more
  1. 2026-09-16 17:55 UTCGHSA enrichment
  2. 2026-09-16 14:09 UTCEPSS rescore
  3. 2026-09-15 16:32 UTCEG score recompute
  4. 2026-09-15 15:59 UTCEG score recompute
  5. 2026-09-15 15:23 UTCEG score recompute
  6. 2026-09-15 15:22 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-91983?
CVE-2026-91983 is a medium vulnerability published on September 15, 2026. Vikunja before 2.6.0 contains an API token scope bypass vulnerability in task read endpoints where authorization fails to inspect query string parameters. Attackers with limited token scopes can use the expand parameter to access restricted data like comments, reactions, and time entries without…
When was CVE-2026-91983 disclosed?
CVE-2026-91983 was first published in the National Vulnerability Database on September 15, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91983 actively exploited?
CVE-2026-91983 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 79.4% of all scored CVEs.
What is the CVSS score of CVE-2026-91983?
CVE-2026-91983 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-91983?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-91983, 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

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