CVE-2026-56765 json
Vikunja - Unauthenticated Instance-Wide Data Breach via Link Share Hash Disclosure Chained with Cross-Project Attachment IDOR
published 7mo ago modified 4mo ago also EUVD-2026-42890 , GHSA-2pv8-4c52-mf8j , GO-2026-4855
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 44%
- public exploits
- 0
- none known
Summary
Vikunja before 2.2.1 contains an authorization flaw where the LinkSharing.ReadAll endpoint exposes share hashes to users with read access, enabling permission escalation to admin-level shares. The GetTaskAttachment endpoint performs permission checks against user-supplied task IDs but fetches attachments by sequential ID without verifying ownership, allowing attackers to download and delete all file attachments across all projects instance-wide.
Patch / fix
- go code.vikunja.io/api 2.2.1
- Vikunja Vikunja 2.2.1
Is CVE-2026-56765 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- total
- Assessed
- 4mo ago
Exploit prediction
0.51% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-11).
Exploits and checks
- github.com https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| CNA | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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 |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| go | code.vikunja.io/api | <2.2.1 all versions |
2.2.1 |
Affected products
- Vikunja Vikunja
Classification
- Weakness
-
- CWE-639 Authorization Bypass Through User-Controlled Key
References
-
github.com
/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j
vendor-advisory, exploit, web, advisory
-
vulncheck.com
/advisories/vikunja-unauthenticated-instance-wide-data-breach-via-link-share-hash-disclosure-chained-with-cros
third-party-advisory
-
github.com
/go-vikunja/vikunja/security/advisories/GHSA-8hp8-9fhr-pfm9
web
-
github.com
/go-vikunja/vikunja/security/advisories/GHSA-jfmm-mjcp-8wq2
web
-
github.com
/go-vikunja/vikunja
package
-
vikunja.io
/changelog/vikunja-v2.2.2-was-released
web
Sources
- CVE List CVE-2026-56765
- GitHub Advisory GHSA-2pv8-4c52-mf8j
- NVD CVE-2026-56765
- OSV GO-2026-4855
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.