Vikunja 2.2.0 before 2.7.0 Permissive CORS Policy Trusting Localhost Origins

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Vikunja from 2.2.0 before 2.7.0 contains a permissive CORS configuration that trusts every localhost and 127.0.0.1 port with credentials, even when service.publicurl is set. Attackers controlling a page on any localhost port can send a credentialed request to the token refresh endpoint and read the returned bearer JWT to take over the logged-in user's account.

Source published

17 Oct 2026 18:46:35 UTC

Source modified

19 Oct 2026 15:00:44 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 7.2 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS 3.1 · 6.3 CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

Vikunja from 2.2.0 before 2.7.0 contains a permissive CORS configuration that trusts every localhost and 127.0.0.1 port with credentials, even when service.publicurl is set. Attackers controlling a page on any localhost port can send a credentialed request to the token refresh endpoint and read the returned bearer JWT to take over the logged-in user's account.

Source published

Oct 17, 2026, 6:46:35 PM (timezone not stated)

Source modified

Oct 19, 2026, 3:00:44 PM (timezone not stated)

Observed here

7 Nov 2026 04:33:21 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 7.2 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Vikunja from 2.2.0 before 2.7.0 contains a permissive CORS configuration that trusts every localhost and 127.0.0.1 port with credentials, even when service.publicurl is set. Attackers controlling a page on any localhost port can send a credentialed request to the token refresh endpoint and read the returned bearer JWT to take over the logged-in user's account.

Source published

17 Oct 2026 19:16:34 UTC

Source modified

19 Oct 2026 21:14:14 UTC

Observed here

25 Oct 2026 05:17:13 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 7.2 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/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

CVSS 3.1 · [email protected] · Secondary · 6.3 CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

## Summary Vikunja ships with `cors.origins` defaulting to `http://127.0.0.1:*` and `http://localhost:*`, and sends `Access-Control-Allow-Credentials: true`, so a page served from any port on the user's own machine may make credentialed cross-origin requests to the API and read the responses. The mandatory `service.publicurl` is appended to that default list rather than replacing it, so a fully configured production deployment still trusts every localhost origin. Combined with the token refresh endpoint, which authenticates with the `vikunja_refresh_token` cookie and returns a bearer JWT in the response body, one `fetch()` from such a page yields a working access token for whoever is logged in, and from there the whole account. ## Vulnerability Details `cors.enable` defaults to true and `cors.origins` defaults to the two localhost wildcards: https://github.com/go-vikunja/vikunja/blob/a881ac39eecd07575a5aede8e74727c28d5fd578/pkg/config/config.go#L495-L497 The middleware is registered with `AllowCredentials: true` and an `UnsafeAllowOriginFunc` that implements the port wildcard through `matchCORSOrigin`, since Echo v5 will not accept a wildcard port itself: https://github.com/go-vikunja/vikunja/blob/a881ac39eecd07575a5aede8e74727c28d5fd578/pkg/routes/routes.go#L263-L281 The detail that turns a development convenience into a production exposure is the last line of configuration handling. Enabling CORS without a public URL is a fatal error, so every deployment sets one, and that value is *appended* to the origin list rather than substituted for it: https://github.com/go-vikunja/vikunja/blob/a881ac39eecd07575a5aede8e74727c28d5fd578/pkg/config/config.go#L828-L830 An operator who configures nothing but their own hostname therefore ends up allowing three origins with credentials: their site, and any port on `localhost` and `127.0.0.1`. There is no supported configuration in which the localhost entries are quietly dropped, and nothing in the logs distinguishes the intended origin from the inherited ones. The escalation path is the refresh endpoint. It is deliberately unauthenticated because it authenticates with the refresh cookie instead of a bearer token, and it returns the new access token in the JSON body: https://github.com/go-vikunja/vikunja/blob/a881ac39eecd07575a5aede8e74727c28d5fd578/pkg/routes/api/v1/login.go#L129-L150 The cookie is `HttpOnly`, but that offers no protection here, because the attacking page never reads the cookie. It issues a credentialed request and the browser attaches the cookie itself. `SetRefreshTokenCookie` marks the cookie `SameSite=None` whenever the public URL is `https`, precisely so the cookie survives split-origin deployments, which is also what allows a cross-site send from a localhost page: https://github.com/go-vikunja/vikunja/blob/a881ac39eecd07575a5aede8e74727c28d5fd578/pkg/modules/auth/auth.go#L84-L104 So a single `fetch('https://vikunja.example.com/api/v1/user/token/refresh', {method: 'POST', credentials: 'include'})` from any page on any localhost port returns a bearer token for the logged-in user, and the CORS response headers permit the page to read it. The token carries the user's full API authority. ## Proof of Concept Three files, built together in one directory and run with: [poc.zip](https://github.com/user-attachments/files/31917334/poc.zip) ``` docker build -f Dockerfile -t poc . && docker run --rm poc ``` - `Dockerfile` builds Vikunja from commit `a881ac39eecd07575a5aede8e74727c28d5fd578` and bakes the reproducer in. - `poc.sh` is the entrypoint. It starts the application on sqlite with `service.publicurl` as the only setting configured, waits for the health check, and runs the exploit. - `exploit.py` registers a user, logs them in, then acts as a page on `http://localhost:31337`: it reads the refresh cookie attributes, sends the CORS preflight, makes the credentialed refresh request, and asks the API who the returned token belongs to. Nothing is stubbed and no internal function is called; everything after startup is ordinary HTTP against the running application. In the output `[+]` lines are measured checks and `[*]` lines are commentary, so only the checks and the final verdict are evidence. A run against `a881ac39eecd07575a5aede8e74727c28d5fd578` prints: ``` [*] Vikunja built from commit a881ac39ee, sqlite, service.publicurl=https://vikunja.example.com. [*] service.publicurl is the only setting configured. cors.enable and cors.origins keep their defaults. [+] The victim logs in and the refresh cookie is issued SameSite=None; Secure, so it is sent cross-site. [+] A page on http://localhost:31337 is allowed to send credentials: Access-Control-Allow-Origin: http://localhost:31337, Access-Control-Allow-Credentials: true [+] That page reads the response of a credentialed refresh, which carries a bearer token: eyJhbGciOiJIUzI1NiIsInR5cCI6... [+] The token authenticates as: 'victim' EXPLOIT SUCCESSFUL ``` ## Suggested Fix The fix is for `service.publicurl` to replace the localhost defaults rather than extend them, so that configuring a deployment narrows the allowed origins instead of widening them. If the localhost entries are retained deliberately for desktop clients, they should not be combined with `AllowCredentials: true`, since it is the combination that allows a third-party origin to read authenticated responses. ## Attribution This vulnerability was found using Google's security automation tooling, abd triaged manually with manual report writing by Ada Logics. Please credit Google and Ada Logics in any advisories.

Source published

9 Oct 2026 20:57:50 UTC

Source modified

19 Oct 2026 21:40:54 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH

Vikunja: Permissive Cross-domain Security Policy trusts every localhost origin which should not be trusted in code.vikunja.io/api. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: .

Source published

19 Oct 2026 21:08:26 UTC

Source modified

19 Oct 2026 21:40:54 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.