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Fencer Intel
medium 5.4

CVE-2026-123526 json

Vikunja before 2.7.1 Mass Assignment via Team external_id Field

published 21d ago modified 2d ago also EUVD-2026-119411 , GHSA-fjrf-gjmg-9v6g

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository go-vikunja/vikunja. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits
0
none known

Summary

Vikunja before 2.7.1 contains a mass assignment vulnerability that allows any authenticated user to set the read-only external_id field through the team create and update endpoints. Attackers can tag a team they create or administer as externally managed, permanently blocking removal of every member and causing SSO members to be dropped from the team at their next login.

Patch / fix

  • go-vikunja vikunja 2.7.1

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2d ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/go-vikunja/vikunja/security/advisories/GHSA-fjrf-gjmg-9v6g referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/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 products

  • go-vikunja vikunja

Classification

Weakness
  • CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes

References

Sources

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.

The maintainers of go-vikunja/vikunja published their own advisory on GitHub. Reviewed sources take precedence over it.