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CVE-2026-55512

nebula-mesh: Unauthenticated OIDC login endpoint allocates unbounded in-memory state entries without rate limiting

5.3 MediumFix available

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. From version 0.2.0 to before version 0.5.0, when OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits. This issue has been patched in version 0.5.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.60%Up 0.3 points since Sep 5, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.3

nebula-mesh: Unauthenticated OIDC login endpoint allocates unbounded in-memory state entries without rate limiting

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. From version 0.2.0 to before version 0.5.0, when OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits. This issue has been patched in version 0.5.0.

Record
CVE-2026-55512
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-400
Updated
2026-11-02
EUVDEUVD-2026-71718 5.3

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. From version 0.2.0 to before version 0.5.0, when OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits. This issue has been patched in version 0.5.0.

Record
EUVD-2026-71718
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
GitHub AdvisoriesGHSA-m3cx-mwpg-32jg 5.3

nebula-mesh: Unauthenticated OIDC login endpoint allocates unbounded in-memory state entries without rate limiting

Summary

When OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits.

Details

The OIDC login route is registered directly by WithOIDC:

  • internal/web/web.go:153 registers w.router.Get("/ui/oidc/login", o.HandleLogin).
  • internal/web/web.go:154 rate-limits only GET /ui/oidc/callback with w.rateLimitMiddleware("auth").

The normal /ui/* route group applies rate limiting to login/register form submissions, but this direct registration happens outside that group:

  • internal/web/web.go:287 through internal/web/web.go:292 show the rate-limited local login, TOTP, and register POST routes.

The OIDC login handler allocates persistent server-side state before redirecting to the configured identity provider:

  • internal/web/oidc.go:105 defines HandleLogin.
  • internal/web/oidc.go:106 creates a random state token.
  • internal/web/oidc.go:112 calls o.rememberState(state).
  • internal/web/oidc.go:122 redirects to o.oauth.AuthCodeURL(state).

The state storage has a TTL but no maximum size:

  • internal/web/oidc.go:24 through internal/web/oidc.go:26 define oidcStateTTL = 10 * time.Minute.
  • internal/web/oidc.go:353 through internal/web/oidc.go:358 sweep expired states and then add the new state to o.states.
  • internal/web/oidc.go:360 through internal/web/oidc.go:373 delete only expired states.

Because the route is unauthenticated and not rate-limited, a remote client can repeatedly request /ui/oidc/login and force live state entries to accumulate for ten minutes. OIDC must be enabled for exposure. No IdP callback, valid credentials, or user interaction is required to trigger the allocation.

Affected version evidence: OIDC login support was introduced by commit 3f46685 (feat(auth): add OIDC operator login (Keycloak/Authentik/Okta/...) (#24)), and git tag --contains 3f46685 --sort=version:refname returns v0.2.0 and every later release through v0.3.8. Pattern checks across all release tags showed the OIDC login route and state allocation are present in v0.2.0 and in every v0.3.x release from v0.3.0 to v0.3.8, and absent from v0.1.x. The current checkout at commit d92dd9a60de291e2bc1caf73b4e9a99567b31ec0 (git describe: v0.3.8-1-gd92dd9a) remains affected.

PoC

Safe local PoC run from a clean checkout at commit d92dd9a60de291e2bc1caf73b4e9a99567b31ec0 on 2026-06-12. The PoC is a temporary Go test that uses httptest and an in-memory OIDC object; it does not start a real server, does not contact an IdP, and uses 1000 requests only to demonstrate linear state growth.

  1. Create a temporary test file internal/web/security_audit_poc_test.go in package web.
  2. Create a test Web UI with newTestWeb(t).
  3. Install a deliberately tiny auth rate limiter: group auth with rate 0.001 and burst 2.
  4. Attach an OIDC instance with an empty states map and an oauth2.Config whose authorization endpoint is https://idp.example.test/auth.
  5. Send 1000 unauthenticated GET /ui/oidc/login requests from the same RemoteAddr through w.ServeHTTP.
  6. Assert no request returns 429 Too Many Requests, then inspect o.stateCount().

Command run:

go test ./internal/web -run 'TestSecurityAuditPOC' -count=1 -v

Observed vulnerable output from this environment:

=== RUN   TestSecurityAuditPOC_OIDCLoginAllocatesUnrateLimitedState
POC_OIDC_STATE_GROWTH attempts=1000 live_states=1000 ttl=10m0s rate_limit_group=auth_burst_2
--- PASS: TestSecurityAuditPOC_OIDCLoginAllocatesUnrateLimitedState (0.10s)
```…
Record
GHSA-m3cx-mwpg-32jg
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-400
Updated
2026-11-02
NVD 5.3

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. From version 0.2.0 to before version 0.5.0, when OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits. This issue has been patched in version 0.5.0.

Record
CVE-2026-55512
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-400
Updated
2026-11-02
OSV 5.3

nebula-mesh: Unauthenticated OIDC login endpoint allocates unbounded in-memory state entries without rate limiting

nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. From version 0.2.0 to before version 0.5.0, when OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits. This issue has been patched in version 0.5.0.

Record
CVE-2026-55512
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-400
Updated
2026-11-02
OSVGHSA-m3cx-mwpg-32jg 5.3

nebula-mesh: Unauthenticated OIDC login endpoint allocates unbounded in-memory state entries without rate limiting

Summary

When OIDC is enabled, GET /ui/oidc/login is reachable without authentication and is registered outside the Web UI rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map for 10m. Expired states are swept lazily, but there is no rate limit or maximum live-state cap on the allocation path. An unauthenticated remote client can therefore grow OIDC.states for the full state TTL, bounded by request throughput rather than by configured auth rate limits.

Details

The OIDC login route is registered directly by WithOIDC:

  • internal/web/web.go:153 registers w.router.Get("/ui/oidc/login", o.HandleLogin).
  • internal/web/web.go:154 rate-limits only GET /ui/oidc/callback with w.rateLimitMiddleware("auth").

The normal /ui/* route group applies rate limiting to login/register form submissions, but this direct registration happens outside that group:

  • internal/web/web.go:287 through internal/web/web.go:292 show the rate-limited local login, TOTP, and register POST routes.

The OIDC login handler allocates persistent server-side state before redirecting to the configured identity provider:

  • internal/web/oidc.go:105 defines HandleLogin.
  • internal/web/oidc.go:106 creates a random state token.
  • internal/web/oidc.go:112 calls o.rememberState(state).
  • internal/web/oidc.go:122 redirects to o.oauth.AuthCodeURL(state).

The state storage has a TTL but no maximum size:

  • internal/web/oidc.go:24 through internal/web/oidc.go:26 define oidcStateTTL = 10 * time.Minute.
  • internal/web/oidc.go:353 through internal/web/oidc.go:358 sweep expired states and then add the new state to o.states.
  • internal/web/oidc.go:360 through internal/web/oidc.go:373 delete only expired states.

Because the route is unauthenticated and not rate-limited, a remote client can repeatedly request /ui/oidc/login and force live state entries to accumulate for ten minutes. OIDC must be enabled for exposure. No IdP callback, valid credentials, or user interaction is required to trigger the allocation.

Affected version evidence: OIDC login support was introduced by commit 3f46685 (feat(auth): add OIDC operator login (Keycloak/Authentik/Okta/...) (#24)), and git tag --contains 3f46685 --sort=version:refname returns v0.2.0 and every later release through v0.3.8. Pattern checks across all release tags showed the OIDC login route and state allocation are present in v0.2.0 and in every v0.3.x release from v0.3.0 to v0.3.8, and absent from v0.1.x. The current checkout at commit d92dd9a60de291e2bc1caf73b4e9a99567b31ec0 (git describe: v0.3.8-1-gd92dd9a) remains affected.

PoC

Safe local PoC run from a clean checkout at commit d92dd9a60de291e2bc1caf73b4e9a99567b31ec0 on 2026-06-12. The PoC is a temporary Go test that uses httptest and an in-memory OIDC object; it does not start a real server, does not contact an IdP, and uses 1000 requests only to demonstrate linear state growth.

  1. Create a temporary test file internal/web/security_audit_poc_test.go in package web.
  2. Create a test Web UI with newTestWeb(t).
  3. Install a deliberately tiny auth rate limiter: group auth with rate 0.001 and burst 2.
  4. Attach an OIDC instance with an empty states map and an oauth2.Config whose authorization endpoint is https://idp.example.test/auth.
  5. Send 1000 unauthenticated GET /ui/oidc/login requests from the same RemoteAddr through w.ServeHTTP.
  6. Assert no request returns 429 Too Many Requests, then inspect o.stateCount().

Command run:

go test ./internal/web -run 'TestSecurityAuditPOC' -count=1 -v

Observed vulnerable output from this environment:

=== RUN   TestSecurityAuditPOC_OIDCLoginAllocatesUnrateLimitedState
POC_OIDC_STATE_GROWTH attempts=1000 live_states=1000 ttl=10m0s rate_limit_group=auth_burst_2
--- PASS: TestSecurityAuditPOC_OIDCLoginAllocatesUnrateLimitedState (0.10s)
```…
Record
GHSA-m3cx-mwpg-32jg
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-400
Updated
2026-11-02
OSVGO-2026-5989 No score

Unauthenticated OIDC login in nebula-mesh allows unbounded memory allocation in github.com/forgekeep/nebula-mesh

When OIDC is enabled, the login endpoint is reachable without authentication and is registered outside the rate-limited auth routes. Every request creates a fresh random OIDC state value and stores it in an in-memory map.

An unauthenticated remote client can grow the state storage, bounded by request throughput rather than by configured auth rate limits, potentially leading to a denial of service.

Record
GO-2026-5989
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/forgekeep/nebula-mesh
Go
 0.2.0 up to 0.5.0
0.5.0
github.com/forgekeep/nebula-mesh
Go
 0.4.0 up to 0.5.0
0.5.0
github.com/juev/nebula-mesh
Go
 0.2.0 and later None known
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-55512 is a medium vulnerability (CVSS 5.3) in Forgekeep Nebula-mesh, published July 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.60%, the 48th percentile. Fixed in github.com/forgekeep/nebula-mesh 0.5.0.

References

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