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CVE-2026-91981

Vikunja before 2.6.0 User Enumeration via v2 API

Description

Vikunja versions before 2.6.0 fail to properly validate link-share tokens in the v2 API user search endpoints. Attackers with a read-only share link can enumerate project users via the projects endpoint and confirm arbitrary usernames exist via the global search endpoint.

Public exploit

An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.

Show the exploits1

References tagged exploit1 reference

Timeline

  1. ID reserved

    By VulnCheck

  2. Published

  3. · 6 days later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-91981, by who scored it
Scored byCVSSScoreVector
VulnCheckCNA (assigner)4.0Medium5.3CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
VulnCheckCNA (assigner)3.1Medium4.3CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
NVDNVD · Deferred4.0Medium5.3CVSS: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
EPSS (exploitation in 30 days)
0.31% · top 76% of all CVEs (9 Nov 2026)
CISA SSVC
Exploitation: poc · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.

Affected products

Affected packages

From reviewed advisories of the GitHub Advisory Database.

References

2

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .