VulnerabilityPublished 2 Aug 2026Updated 3 Aug 2026

CVE-2026-68581: vikunja · Incorrect Authorization

Affects vikunjaSource CVE Database V5

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Not known to be exploited · CVSS 8.6 High : upgrade to 2.4.0 soon.

Data as of 31 Oct 2026, 08:20 UTC

CVSS 4.0 base score

8.6High

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.4.0

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: High
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the vulnerable system. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the vulnerable system.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 2 Aug 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 to 2.4.0.

Affected software

Product	Affected	Fixed in
go-vikunjavikunja	Affected >=0.22.0 <2.4.0	Fixed in 2.4.0
Gogithub.com/go-vikunja/vikunja`pkg:golang/github.com/go-vikunja/vikunja`Other threats	Affected =0.22.0 <=2.3.0	Fixed in–

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AI-suggested

Upgrade to Vikunja version 2.4.0 or later, where this authorization flaw is fixed. No other official remediation or temporary workaround is indicated. Patch status is not explicitly stated but the fix version is known.

Description

Executive Summary Vikunja accepts both regular-user JSON Web Tokens (JWTs) and link-share JWTs through its generic authenticated API route group. A link-share JWT resolves to a `models.LinkSharing` principal whose `GetID()` method returns the numeric `link_shares.id`. The API-token management model then treats that generic numeric value as a `users.id` when it creates, lists, and deletes API tokens. Because `users.id` and `link_shares.id` are independent positive sequences, a link share whose ID equals another user's ID is treated as that user by `/api/v1/tokens`. An ordinary authenticated attacker can obtain a target's numeric user ID through authenticated user search and create link shares on an attacker-writable project until the link-share sequence reaches that value. The colliding link-share principal can then list the target's API-token metadata, issue a new API token owned by the target, and delete target-owned API tokens. The newly issued token operates with attacker-selected valid API scopes under the target user's existing permissions. I reviewed the vulnerable `v2.3.0` source, the introducing commit, the stable tag history, and the inspected main revision directly. I also reviewed the recorded local HTTP and native-router validation results. Dynamic testing used only a local `v2.3.0` Docker deployment with PostgreSQL and synthetic data; I did not test any public, hosted, or otherwise external instance. Historical tags were checked from source rather than exercised dynamically. | Field | Value | | --- | --- | | Product | Vikunja API | | Status | Validated; disclosure-ready | | Confirmed affected stable versions | `v0.22.0` through `v2.3.0`, inclusive | | Nearest confirmed unaffected stable version | `v0.21.0` | | Introducing commit | `e6b25bd57b537ef9a72b5acdadf446ca5ef77bfa` | | Latest inspected affected main revision | `95b7e673fb5ee407498fa4b13e8b4c57847a4a0b` | | Fixed version | Unknown; no verified fix commit or release was identified | | Severity | High, CVSS v3.1 score 8.1 | | Vector | `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N` | | Weakness | Primary: CWE-863 (Incorrect Authorization); secondary: CWE-639 | The stable range is source-based. The issue first became reachable when commit `e6b25bd57b...` added the authenticated API-token CRUD routes while retaining the generic `web.Auth.GetID()` ownership model. `v0.21.0` does not contain the API-token model or these routes. All containing stable tags from `v0.22.0` through `v2.3.0` retain the vulnerable source-to-sink tuple. Downstream forks and vendor-specific builds were not assessed. ## Background ### Two authenticated principal types share one numeric interface Vikunja's authenticated route group is protected by a common token middleware. That middleware can establish a regular user, an API-token owner, or a link share as the request's `web.Auth` principal. The `/api/v1/tokens` handlers are registered on this generic group in `pkg/routes/routes.go`: ```go a.Use(SetupTokenMiddleware()) // API Tokens apiTokenProvider := &handler.WebHandler{ EmptyStruct: func() handler.CObject { return &models.APIToken{} }, } a.GET("/tokens", apiTokenProvider.ReadAllWeb) a.PUT("/tokens", apiTokenProvider.CreateWeb) a.DELETE("/tokens/:token", apiTokenProvider.DeleteWeb) ``` The security-sensitive detail is that authentication answers *which object is the principal*, while `web.Auth.GetID()` exposes only an untyped integer. A regular user's ID belongs to the `users` namespace. A link-share ID belongs to the separately allocated `link_shares` namespace. Equality between those integers does not imply that the principals represent the same actor. ### Link-share authentication preserves the share-row ID `pkg/modules/auth/auth.go` creates a link-share JWT with the share's numeric ID and later resolves that token to a `models.LinkSharing` object: ```go claims["type"] = AuthTypeLinkShare claims["id"] = share.ID claims["hash"] = share.Hash claims["project_id"] = share.ProjectID // ... if typ == AuthTypeLinkShare && config.ServiceEnableLinkSharing.GetBool() { s := db.NewSession() defer s.Close() return models.GetLinkShareFromClaims(s, claims) } ``` The `LinkSharing` model declares its own positive auto-incrementing key and returns it unchanged through the generic interface in `pkg/models/link_sharing.go`: ```go type LinkSharing struct { ID int64 `xorm:"bigint autoincr not null unique pk" json:"id" param:"share"` // ... } func (share *LinkSharing) GetID() int64 { return share.ID } ``` Link shares are expected to act within the shared project's permission boundary. API-token management is instead a user-account credential boundary: tokens are owned by users and can authorize future requests as those users. The normal invariant should therefore be that only a positively identified regular-user principal may enter API-token management, and its user ID must be used as the owner key. ### Attacker capabilities The validated attacker is an ord

Impact

An authenticated attacker can impersonate a target user in the API token management endpoints by exploiting the flawed principal type validation. This allows the attacker to manage the target user's API tokens, including issuing new tokens with arbitrary scopes, potentially leading to unauthorized access and actions under the target user's identity. The vulnerability has a high severity with a CVSS 4.0 score of 8.6.

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What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Aug 2026, 14:23 UTC

Technical details

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