CVE-2026-49998 Centrifugo: Dynamic JWKS key cache keyed only by `kid` allows cross-issuer JWT authentication bypass
Attackers can bypass JWT authentication by exploiting a JWKS cache flaw that reuses keys across different issuers in Centrifugo.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-49998?
CVE-2026-49998 is a high-severity authentication bypass vulnerability in centrifugal centrifugo, published on 16 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-347
Which versions are affected by CVE-2026-49998?
15 open source packages ship an affected version, including github.com/centrifugal/centrifugo, github.com/centrifugal/centrifugo/v3 and github.com/centrifugal/centrifugo/v4.
| Package | Affected | Fixed in |
|---|---|---|
github.com/centrifugal/centrifugo Go | All versions | None |
github.com/centrifugal/centrifugo Go | All versions to 2.4.0 | None |
github.com/centrifugal/centrifugo Go | All versions to 2.4.0 | None |
github.com/centrifugal/centrifugo/v3 Go | All versions | None |
github.com/centrifugal/centrifugo/v3 Go | All versions to 3.2.3 | None |
github.com/centrifugal/centrifugo/v3 Go | All versions to 3.2.3 | None |
9 more packages
github.com/centrifugal/centrifugo/v4 Go | All versions | None |
github.com/centrifugal/centrifugo/v4 Go | All versions to 4.1.5 | None |
github.com/centrifugal/centrifugo/v4 Go | All versions to 4.1.5 | None |
github.com/centrifugal/centrifugo/v5 Go | All versions | None |
github.com/centrifugal/centrifugo/v5 Go | All versions to 5.4.9 | None |
github.com/centrifugal/centrifugo/v5 Go | All versions to 5.4.9 | None |
github.com/centrifugal/centrifugo/v6 Go | All versions | 6.8.1 |
github.com/centrifugal/centrifugo/v6 Go | All versions | 6.8.1 |
github.com/centrifugal/centrifugo/v6 Go | All versions | 6.8.1 |
How do I fix CVE-2026-49998?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-49998 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49998 exists.
Sources
Also known as GHSA-g6vg-wj8f-48cj, GO-2026-5872.