nebula-mesh: Web UI lacks CSRF tokens on /ui/* mutating endpoints

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.

nebula-mesh is a self-hosted control plane for Slack Nebula mesh virtual private network. Prior to version 0.3.3, every /ui/* POST / PUT / PATCH / DELETE route processes the request as soon as the session cookie validates. SameSite=Lax on the session cookie prevents most cross-site form submits but does not protect: top-level form-submit navigations from third-party pages (some browsers still send Lax cookies on top-level POSTs); same-registrable-domain attackers (sibling-subdomain XSS, subdomain takeover); the GET /ui/logout route, which a third-party <img src=".../ui/logout"> can force-trigger. This issue has been patched in version 0.3.3.

Source published

28 Jul 2026 17:56:29 UTC

Source modified

28 Jul 2026 19:36:36 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 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

nebula-mesh is a self-hosted control plane for Slack Nebula mesh virtual private network. Prior to version 0.3.3, every /ui/* POST / PUT / PATCH / DELETE route processes the request as soon as the session cookie validates. SameSite=Lax on the session cookie prevents most cross-site form submits but does not protect: top-level form-submit navigations from third-party pages (some browsers still send Lax cookies on top-level POSTs); same-registrable-domain attackers (sibling-subdomain XSS, subdomain takeover); the GET /ui/logout route, which a third-party <img src=".../ui/logout"> can force-trigger. This issue has been patched in version 0.3.3.

Source published

28 Jul 2026 19:17:34 UTC

Source modified

23 Oct 2026 23:10:00 UTC

Observed here

25 Oct 2026 12:17:26 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 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/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

Every `/ui/*` POST / PUT / PATCH / DELETE route processes the request as soon as the session cookie validates. `SameSite=Lax` on the session cookie prevents most cross-site form submits but does not protect: - top-level form-submit navigations from third-party pages (some browsers still send Lax cookies on top-level POSTs) - same-registrable-domain attackers (sibling-subdomain XSS, subdomain takeover) - the `GET /ui/logout` route, which a third-party `<img src=".../ui/logout">` can force-trigger The admin UI signs CA certificates, mints API keys, rotates / retires / deletes CAs, disables operators, and changes server settings. CSRF here is a real privilege escalation, not just annoyance. ## Affected All released versions up to v0.3.2. ## Suggested fix Double-submit cookie: a 32-byte `crypto/rand` token in a non-HttpOnly `_csrf` cookie, echoed in either `X-CSRF-Token` (htmx) or a `_csrf` form field (HTML forms). Compared in constant time. Rotated on every privilege transition (`Login`, OIDC `StartAuthenticatedSession`, `CompleteTwoFactor`, `Logout`) so pre-auth fixation cannot survive promotion. Rejections audit-logged as `ui.csrf.rejected` with reason; response body stays opaque. `/ui/logout` becomes POST so it is no longer reachable via `<img>` tags. Fix coordinates with the Secure-cookie advisory disclosed concurrently — the `_csrf` cookie inherits the same `Secure`-attribute derivation. ## Reproducer With an authenticated operator session in browser tab A, open the following minimal HTML in any other tab: ```html <form action="https://nebula.example.com/ui/cas/{ca-id}/delete" method="POST"> <button>Click for free puppy</button> </form> ``` Click. The CA is deleted — the server processes the POST because the session cookie is automatically attached and there is no other check. The same trick works for force-rotate, retire, mint API keys, disable operators, etc. Alternative force-logout: `<img src="https://nebula.example.com/ui/logout">` placed on an attacker's page logs out any visiting authenticated operator. No interaction required. ## Notes - Multipart and JSON endpoints don't exist in the current UI surface. Future additions must rely on the header path because `r.PostFormValue` only reads `application/x-www-form-urlencoded` bodies. The middleware's package comment documents this. - The patch assumes nebula-mgmt is the sole authority on its registrable domain. A compromised sibling subdomain can still set parent-domain cookies and forge matches; SameSite=Lax does not prevent that. Documented in the patch.

Source published

8 Jun 2026 23:09:21 UTC

Source modified

17 Jun 2026 00:26:22 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:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH

nebula-mesh's web UI lacks CSRF tokens on /ui/* mutating endpoints in github.com/juev/nebula-mesh

Source published

16 Jun 2026 23:55:18 UTC

Source modified

17 Jun 2026 00:15:12 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.