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CVE-2026-49998

Centrifugo: Dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass

8.2 HighFix available

Centrifugo is an open-source scalable real-time messaging server. Prior to 6.8.1, Centrifugo dynamic JWKS endpoint verification could reuse a key for one allowed issuer to verify a JWT for another allowed issuer because the JWKS cache and singleflight lookup were keyed only by JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or trust-domain namespace, affecting client.token.jwks_public_endpoint, client.subscription_token.jwks_public_endpoint, internal/jwks/cache.go, and internal/jwks/manager.go. This issue is fixed in version 6.8.1.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.22%Unchanged since Jul 17, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.2

Centrifugo: Dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass

Centrifugo is an open-source scalable real-time messaging server. Prior to 6.8.1, Centrifugo dynamic JWKS endpoint verification could reuse a key for one allowed issuer to verify a JWT for another allowed issuer because the JWKS cache and singleflight lookup were keyed only by JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or trust-domain namespace, affecting client.token.jwks_public_endpoint, client.subscription_token.jwks_public_endpoint, internal/jwks/cache.go, and internal/jwks/manager.go. This issue is fixed in version 6.8.1.

Record
CVE-2026-49998
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
EUVDEUVD-2026-45015 8.2

Centrifugo is an open-source scalable real-time messaging server. Prior to 6.8.1, Centrifugo dynamic JWKS endpoint verification could reuse a key for one allowed issuer to verify a JWT for another allowed issuer because the JWKS cache and singleflight lookup were keyed only by JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or trust-domain namespace, affecting client.token.jwks_public_endpoint, client.subscription_token.jwks_public_endpoint, internal/jwks/cache.go, and internal/jwks/manager.go. This issue is fixed in version 6.8.1.

Record
EUVD-2026-45015
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-g6vg-wj8f-48cj 8.2

Centrifugo's dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass

Summary

Centrifugo's dynamic JWKS endpoint feature can verify a JWT for one allowed issuer using a public key cached from another allowed issuer. The JWKS cache and singleflight lookup are keyed only by the JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or other trust-domain namespace.

In a documented multi-issuer dynamic JWKS configuration, an attacker who can obtain or mint a valid token for issuer/tenant A can authenticate as issuer/tenant B if both JWKS documents use the same kid value and tenant A's key is cached first. This affects connection token verification and subscription token verification because both paths use the same JWKS verification manager.

Details

The vulnerable path is reachable when either of these shipped configuration options is set to a templated JWKS URL using values derived from JWT iss or aud claims:

  • client.token.jwks_public_endpoint
  • client.subscription_token.jwks_public_endpoint

Relevant shipped config fields are defined in internal/configtypes/types.go:59-65, mapped into verifier configuration in internal/confighelpers/jwt.go:36-41, and exposed in the generated config schema at internal/cli/configdoc/schema.json:3927, 3947, 3967, 3987, 4069, 4089, 4109, and 4129. Dynamic JWKS endpoints based on iss and aud are documented in the project changelog at CHANGELOG.md:107.

External clients control JWT connection and subscription tokens:

  • Connection tokens reach VerifyConnectToken from internal/client/handler.go:350-352.
  • Normal subscription tokens reach VerifySubscribeToken from internal/client/handler.go:769-775.
  • Subscription refresh tokens reach VerifySubscribeToken from internal/client/handler.go:628-632.

The verifier must parse token claims before signature verification to resolve the dynamic JWKS endpoint:

  • VerifyConnectToken parses without verification at internal/jwtverify/token_verifier_jwt.go:528-535, extracts template variables before signature verification at internal/jwtverify/token_verifier_jwt.go:539-548, then validates claims only after signature verification at internal/jwtverify/token_verifier_jwt.go:557-560.
  • VerifySubscribeToken follows the same pattern at internal/jwtverify/token_verifier_jwt.go:700-732.

The problem is that the JWKS cache lookup ignores the endpoint/trust domain selected by those token variables. internal/jwtverify/token_verifier_jwt.go:242-245 passes only the JWT header kid plus token-derived variables to the JWKS manager:

func (j *jwksManager) verify(token *jwt.Token, tokenVars map[string]any) error {
    kid := token.Header().KeyID

    key, err := j.Manager.FetchKey(context.Background(), kid, tokenVars)

internal/jwks/manager.go:96-117 checks cache and singleflight using only kid:

func (m *Manager) FetchKey(ctx context.Context, kid string, tokenVars map[string]any) (*JWK, error) {
    if kid == "" {
        return nil, ErrKeyIDNotProvided
    }

    if m.useCache {
        key, err := m.cache.Get(kid)
        if err == nil {
            return key, nil
        }
    }

    v, err, _ := m.group.Do(kid, func() (any, error) {
        return m.fetchKey(ctx, kid, tokenVars)
    })

The resolved JWKS URL is computed only later in internal/jwks/manager.go:133-149:

func (m *Manager) fetchKey(ctx context.Context, kid string, tokenVars map[string]any) (*JWK, error) {
    jwkURL := m.url.ExecuteString(tokenVars)
    ...
    req, err := http.NewRequestWithContext(ctx, http.MethodGet, jwkURL, nil)

The TTL cache also stores and retrieves keys only by kid at internal/jwks/cache_ttl.go:82-101:

func (tc *TTLCache) Add(key *JWK) error {
    ...
    tc.items[key.Kid] = item
}

func (tc *TTLCache) Get(kid string) (*JWK, error) {
    ...
    item, ok := tc.items[kid]

As a result, a key fetched from tenant A's JWKS endpoint can be reused to verify a token claiming tenant B before tenant B's JWKS endpoint is…

Record
GHSA-g6vg-wj8f-48cj
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
NVD 8.2

Centrifugo is an open-source scalable real-time messaging server. Prior to 6.8.1, Centrifugo dynamic JWKS endpoint verification could reuse a key for one allowed issuer to verify a JWT for another allowed issuer because the JWKS cache and singleflight lookup were keyed only by JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or trust-domain namespace, affecting client.token.jwks_public_endpoint, client.subscription_token.jwks_public_endpoint, internal/jwks/cache.go, and internal/jwks/manager.go. This issue is fixed in version 6.8.1.

Record
CVE-2026-49998
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
OSV 8.2

Centrifugo: Dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass

Centrifugo is an open-source scalable real-time messaging server. Prior to 6.8.1, Centrifugo dynamic JWKS endpoint verification could reuse a key for one allowed issuer to verify a JWT for another allowed issuer because the JWKS cache and singleflight lookup were keyed only by JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or trust-domain namespace, affecting client.token.jwks_public_endpoint, client.subscription_token.jwks_public_endpoint, internal/jwks/cache.go, and internal/jwks/manager.go. This issue is fixed in version 6.8.1.

Record
CVE-2026-49998
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
OSVGHSA-g6vg-wj8f-48cj 8.2

Centrifugo's dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass

Summary

Centrifugo's dynamic JWKS endpoint feature can verify a JWT for one allowed issuer using a public key cached from another allowed issuer. The JWKS cache and singleflight lookup are keyed only by the JWT header kid, not by the resolved JWKS endpoint, issuer, audience, or other trust-domain namespace.

In a documented multi-issuer dynamic JWKS configuration, an attacker who can obtain or mint a valid token for issuer/tenant A can authenticate as issuer/tenant B if both JWKS documents use the same kid value and tenant A's key is cached first. This affects connection token verification and subscription token verification because both paths use the same JWKS verification manager.

Details

The vulnerable path is reachable when either of these shipped configuration options is set to a templated JWKS URL using values derived from JWT iss or aud claims:

  • client.token.jwks_public_endpoint
  • client.subscription_token.jwks_public_endpoint

Relevant shipped config fields are defined in internal/configtypes/types.go:59-65, mapped into verifier configuration in internal/confighelpers/jwt.go:36-41, and exposed in the generated config schema at internal/cli/configdoc/schema.json:3927, 3947, 3967, 3987, 4069, 4089, 4109, and 4129. Dynamic JWKS endpoints based on iss and aud are documented in the project changelog at CHANGELOG.md:107.

External clients control JWT connection and subscription tokens:

  • Connection tokens reach VerifyConnectToken from internal/client/handler.go:350-352.
  • Normal subscription tokens reach VerifySubscribeToken from internal/client/handler.go:769-775.
  • Subscription refresh tokens reach VerifySubscribeToken from internal/client/handler.go:628-632.

The verifier must parse token claims before signature verification to resolve the dynamic JWKS endpoint:

  • VerifyConnectToken parses without verification at internal/jwtverify/token_verifier_jwt.go:528-535, extracts template variables before signature verification at internal/jwtverify/token_verifier_jwt.go:539-548, then validates claims only after signature verification at internal/jwtverify/token_verifier_jwt.go:557-560.
  • VerifySubscribeToken follows the same pattern at internal/jwtverify/token_verifier_jwt.go:700-732.

The problem is that the JWKS cache lookup ignores the endpoint/trust domain selected by those token variables. internal/jwtverify/token_verifier_jwt.go:242-245 passes only the JWT header kid plus token-derived variables to the JWKS manager:

func (j *jwksManager) verify(token *jwt.Token, tokenVars map[string]any) error {
    kid := token.Header().KeyID

    key, err := j.Manager.FetchKey(context.Background(), kid, tokenVars)

internal/jwks/manager.go:96-117 checks cache and singleflight using only kid:

func (m *Manager) FetchKey(ctx context.Context, kid string, tokenVars map[string]any) (*JWK, error) {
    if kid == "" {
        return nil, ErrKeyIDNotProvided
    }

    if m.useCache {
        key, err := m.cache.Get(kid)
        if err == nil {
            return key, nil
        }
    }

    v, err, _ := m.group.Do(kid, func() (any, error) {
        return m.fetchKey(ctx, kid, tokenVars)
    })

The resolved JWKS URL is computed only later in internal/jwks/manager.go:133-149:

func (m *Manager) fetchKey(ctx context.Context, kid string, tokenVars map[string]any) (*JWK, error) {
    jwkURL := m.url.ExecuteString(tokenVars)
    ...
    req, err := http.NewRequestWithContext(ctx, http.MethodGet, jwkURL, nil)

The TTL cache also stores and retrieves keys only by kid at internal/jwks/cache_ttl.go:82-101:

func (tc *TTLCache) Add(key *JWK) error {
    ...
    tc.items[key.Kid] = item
}

func (tc *TTLCache) Get(kid string) (*JWK, error) {
    ...
    item, ok := tc.items[kid]

As a result, a key fetched from tenant A's JWKS endpoint can be reused to verify a token claiming tenant B before tenant B's JWKS endpoint is…

Record
GHSA-g6vg-wj8f-48cj
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
OSVGO-2026-5872 No score

Centrifugo's dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass in github.com/centrifugal/centrifugo

Centrifugo's dynamic JWKS key cache keyed only by kid allows cross-issuer JWT authentication bypass in github.com/centrifugal/centrifugo

Record
GO-2026-5872
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/centrifugal/centrifugo/v6
Go
 through 6.8.0
6.8.1
github.com/centrifugal/centrifugo/v5
Go
 through 5.4.9 None known
github.com/centrifugal/centrifugo/v4
Go
 through 4.1.5 None known
github.com/centrifugal/centrifugo/v3
Go
 through 3.2.3 None known
github.com/centrifugal/centrifugo
Go
 through 2.4.0 None known
github.com/centrifugal/centrifugo/v6
Go
 before 6.8.1
6.8.1
github.com/centrifugal/centrifugo
Go
 All versions None known
github.com/centrifugal/centrifugo/v3
Go
 All versions None known
github.com/centrifugal/centrifugo/v4
Go
 All versions None known
github.com/centrifugal/centrifugo/v5
Go
 All versions 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
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2026-49998 is a high vulnerability (CVSS 8.2) in Centrifugal Centrifugo, published July 1, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in github.com/centrifugal/centrifugo/v6 6.8.1.

References

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