CVE-2026-49478Network attack vectorHinoki check available

Token disclosure and key substitution via redirects

Published Aug 13, 2026 · Updated Aug 13, 2026

SSRF in Sigstore Fulcio before 1.8.6 allows remote attackers controlling an OIDC issuer to reach internal hosts through discovery redirects. The OIDC discovery client follows redirects across host boundaries, while bearerTokenTransport attaches a Kubernetes ServiceAccount token without confirming that the request host matches the issuer and caches substituted JWKS keys. Exploitation requires control of a configured issuer or matching Kubernetes meta-issuer and can disclose the token or validate identities signed with attacker-controlled keys.

CVSS severity8.7
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

SSRF in Sigstore Fulcio before 1.8.6 allows remote attackers controlling an OIDC issuer to reach internal hosts through discovery redirects. The OIDC discovery client follows redirects across host boundaries, while bearerTokenTransport attaches a Kubernetes ServiceAccount token without confirming that the request host matches the issuer and caches substituted JWKS keys. Exploitation requires control of a configured issuer or matching Kubernetes meta-issuer and can disclose the token or validate identities signed with attacker-controlled keys.

The record

CVE
CVE-2026-49478
Published
Aug 13, 2026
Updated
Aug 13, 2026
Vendor
Sigstore
Product
Fulcio
Classifications
CWE-918, T1199
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.8.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sigstore · Fulcioversion=< 1.8.6

Published CVSS scores

8.2GitHub Security AdvisoryCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
8.7GitHub CNACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1199Trusted Relationship

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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