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Noroxi
CVE-2026-91983· NVD / CVE Program· CNA VulnCheck

Vikunja before 2.6.0 API Token Scope Bypass via expand Parameter

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.30% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: go-vikunja vikunja 2.6.0.

Low priority for now. Upgrade to go-vikunja vikunja 2.6.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.3 · v4.0—No exploit Fix available
Published
Sep 15, 2026
Updated
Sep 16, 2026
EPSS
0.3% · 21th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
5.3
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • go-vikunja vikunja

    • 2.6.0not affected
    • 1.0.0 and later · before 2.6.0affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Gocode.vikunja.io/apifrom 0—
Gocode.vikunja.io/apifrom 1.0.0 · before 2.6.02.6.0

Same product

go-vikunja: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-68582Vikunja 0.24.0 Broken Object Level Authorization via Link-Share Token
    37Monitor
  • CVE-2026-91985Vikunja before 2.6.0 Privilege Escalation via Link Share Hash
    34Monitor
  • CVE-2026-91973Vikunja before 2.6.0 Authentication Bypass via CalDAV BasicAuth
    34Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-91981Sep 15, 2026 · Vikunja before 2.6.0 User Enumeration via v2 API
    21Monitor
  • ← EarlierCVE-2026-91982Sep 15, 2026 · Vikunja before 2.6.0 TOTP Secret Disclosure via API
    21Monitor
  • Later →CVE-2026-91984Sep 15, 2026 · Vikunja before 2.6.0 Broken Object-Level Authorization via task-position
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
go-vikunja vikunja2.6.0Vendor (CNA)
Go:code.vikunja.io/api2.6.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-6858144 days apartVikunja 0.22.0 through 2.3.0 Authentication Bypass via Principal ID Collision
    34Monitor
  • CVE-2026-11191832 days apartVikunja 1.0.0-rc0 before 2.7.0 Cross-Tenant Task Position Writes via Saved Filter Creation
    21Monitor
  • CVE-2026-11192132 days apartVikunja 0.13.0 before 2.7.0 Incorrect Authorization in Link Share Deletion
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
X

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records