VulnerabilityPublished 15 Sep 2026

CVE-2026-91980: vikunja · Information Exposure

Affects vikunjaSource CVE Database V5

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Not known to be exploited · CVSS 4.3 Medium : upgrade to 2.6.0 when convenient.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score

4.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.6.0

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade vikunja and github.com/go-vikunja/vikunja to 2.6.0.

Affected software

Product	Affected	Fixed in
go-vikunjavikunja	Affected <2.6.0	Fixed in 2.6.0
Gogithub.com/go-vikunja/vikunja`pkg:golang/github.com/go-vikunja/vikunja`Other threats	Affected <2.6.0	Fixed in 2.6.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The vendor's recommended fix is to enforce access control checks to ensure the caller has permission to access the team being attached to a project, not just project admin rights. If you cannot patch yet, restrict project creation and team attachment permissions to trusted users if possible.

Description

### Summary When you share a project with a team, the API lets you attach any team on the instance, including teams you have nothing to do with, as long as you're an admin of the project. Listing a project's teams then returns each team's full member roster. So any logged-in user can spin up a throwaway project, attach team IDs one by one, and read back the name, description, and complete member list of every team on the instance. Normally you can only see teams you belong to; this path ignores that. ### Details Sharing a project with a team is a two-step flow: you PUT a team to the project, then you GET the project's teams to see them. The share endpoint only enforces that you're an admin of the target project, it doesn't care whether the team you're referencing is one you're allowed to see. Any existing team ID is accepted. The listing endpoint is even more permissive: read access to the project is enough, which you obviously have on a project you created. And its response isn't just a list of team names, it includes each team's description, creator, and a full members array with every member's username, display name, and admin flag. Put together, an attacker who owns a single project can walk the team ID space and pull the roster of every team in the instance, including teams they aren't a member of. This contradicts how team visibility works everywhere else in the product, where you only ever see teams you belong to. Emails are stripped from the roster, so what leaks is identities and org structure rather than contact details. The fix is to require that the caller actually has access to the team they're attaching, not just to the project. ### PoC The attacker needs nothing but an ordinary account. 1. Create a throwaway project you own: 2. Attach team IDs one by one (sweep the range you want): ``` PUT /api/v1/projects/<your_project_id>/teams {<SNIP>, "team_id": <N>, <SNIP>} ``` 3. Read them back with their rosters: ``` GET /api/v1/projects/<your_project_id>/teams ``` Each entry contains the team name, description, creator, and a members array with every member's username, display name, and admin flag, for teams you are not a member of. ### Impact Information disclosure of the instance-wide team directory: team names, descriptions, and full membership, for teams the attacker has no relationship with. This maps out the organisation's group structure and who belongs where, useful for targeting and social engineering. Any authenticated account is enough; no share link, no admin rights, no victim interaction.

Impact

The vulnerability results in unauthorized disclosure of sensitive organizational information, including team names, descriptions, creators, and complete membership lists with usernames and admin status. This exposure can facilitate reconnaissance, targeted social engineering, and mapping of internal group structures. No direct impact on data integrity or availability is indicated. Exploitation requires only an authenticated user account and no special privileges beyond project creation.

Summary

The go-vikunja vikunja project sharing API permits a user who is an admin of a project to attach any team on the instance to that project without verifying if the user has access to that team. Subsequently, the user can list all teams attached to the project and retrieve detailed information about each team, including full member rosters with usernames, display names, and admin flags. This bypasses the normal team visibility model where users only see teams they belong to. An attacker with any authenticated account can create a throwaway project, attach team IDs iteratively, and harvest the membership data of all teams on the instance. The vulnerability affects versions >=0 and <2.6.0. The disclosed information excludes emails but reveals organizational structure and membership useful for targeting and social engineering. The fix involves enforcing access checks on the team being attached, not just project admin rights.

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Affected software

Description

AI analysisMachine-generated, updated 9 Oct 2026, 22:47 UTC

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