Centrifugo: SSRF via unverified JWT claims interpolated into dynamic JWKS endpoint URL

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

EPSS

• CVE-2026-32301: 0.27% estimated exploitation activity in the next 30 days; percentile 19.02 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Centrifugo is vulnerable to Server-Side Request Forgery (SSRF) when configured with a dynamic JWKS endpoint URL using template variables (e.g. {{tenant}}). An unauthenticated attacker can craft a JWT with a malicious iss or aud claim value that gets interpolated into the JWKS fetch URL before the token signature is verified, causing Centrifugo to make an outbound HTTP request to an attacker-controlled destination. Details In internal/jwtverify/tokenverifierjwt.go, the functions VerifyConnectToken and VerifySubscribeToken follow this flawed order of operations: 1. Token is parsed without verification: jwt.ParseNoVerify([]byte(t)) 2. Claims are decoded from the unverified token 3. validateClaims() runs — extracting named regex capture groups from issuerregex/audienceregex into tokenVars map using attacker-controlled iss/aud claim values 4. verifySignatureByJWK(token, tokenVars) is called — passing attacker-controlled tokenVars to the JWKS manager 5. In internal/jwks/manager.go,…

Published by the source

13 Mar 2026, 20:03 UTC

Last modified by the source

27 Mar 2026, 21:16 UTC

Source last checked

26 Oct 2026, 15:18 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-j77h-rr39-c552

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# Patch Next advisory brief: CVE-2026-32301

Advisory: Centrifugo: SSRF via unverified JWT claims interpolated into dynamic JWKS endpoint URL
IDs: CVE-2026-32301, GHSA-j77h-rr39-c552
Record: https://patchnext.com/advisories/cve-2026-32301 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/centrifugal/centrifugo/v6 6.7.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/centrifugal/centrifugo/v5: affected <= 5.4.9
- Go github.com/centrifugal/centrifugo/v4: affected <= 4.1.5
- Go github.com/centrifugal/centrifugo/v3: affected <= 3.2.3
- Go github.com/centrifugal/centrifugo/v6: affected <= 6.6.2; fixed in 6.7.0
- Go github.com/centrifugal/centrifugo: affected <= 2.4.0

## Suggested inspection (read-only)
- Go github.com/centrifugal/centrifugo/v5: check the installed version with your package manager.
- Go github.com/centrifugal/centrifugo/v4: check the installed version with your package manager.
- Go github.com/centrifugal/centrifugo/v3: check the installed version with your package manager.
- Go github.com/centrifugal/centrifugo/v6: check the installed version with your package manager.
- Go github.com/centrifugal/centrifugo: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/centrifugal/centrifugo/v5, github.com/centrifugal/centrifugo/v4, github.com/centrifugal/centrifugo/v3, github.com/centrifugal/centrifugo/v6, github.com/centrifugal/centrifugo.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-j77h-rr39-c552 (GitHub-reviewed advisory GHSA-j77h-rr39-c552 lists affected ranges: Go github.com/centrifugal/centrifugo/v6 >=0 =0 =0 =0 =0 <=5.4.9)

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