CVE-2026-81829: Smallrye-jwt: quarkus-smallrye-jwt: smallrye-jwt: unauthenticated same-origin ssrf via unsanitized jwt kid header in awsalbkeyresolver

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-10-09
Weakness: CWE-22

Description

A flaw was found in SmallRye JWT's AwsAlbKeyResolver, which is used by applications to verify JSON Web Tokens signed by AWS Application Load Balancers. When the AWS_ALB key provider is configured, the resolver constructs the key-fetch URL by directly concatenating the attacker-controlled kid header value from an inbound JWT without sanitizing path traversal characters or query-string separators. This allows an unauthenticated remote attacker to force the application server to issue GET requests to arbitrary paths on the same origin as the configured key endpoint. As a result, non-public endpoints or internal data reachable on that origin may be read by the attacker before JWT signature verification takes place.

Affected products

Red Hat build of Quarkus: all versions
Red Hat Exploit Intelligence: all versions
Red Hat build of Apicurio Registry 3: all versions
Red Hat JBoss Enterprise Application Platform 8: all versions
Red Hat JBoss Enterprise Application Platform Expansion Pack: all versions

References

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