OpenAM: WebAuthn Java deserialization RCE via ObjectInputFilter depth>1 bypass

Exploitation

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

CVSS 4.0

9.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-62263: 0.86% estimated exploitation activity in the next 30 days; percentile 58.57 (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 The GHSA-6c99-87fr-6q7r fix wrapped WebAuthn authenticator deserialization in an ObjectInputFilter meant to allow only AuthenticatorImpl, but it short-circuits to ALLOWED for any object at stream depth 1. Because the Java serialization filter is consulted for every class in the graph (and depth == 1 only for the root's concrete class), the allowlist constrains only the root and leaves the entire nested graph unchecked. Impact An attacker can craft a stream rooted at AuthenticatorImpl with an arbitrary gadget chain nested inside. The gadget's readObject/readResolve executes during readObject() — before the cast and before any assertion verification — enabling remote code execution when a gadget is on the classpath. The deserialization sink is reached pre-authentication via an attacker-chosen userHandle.

Published by the source

24 Jul 2026, 21:08 UTC

Last modified by the source

24 Jul 2026, 21:08 UTC

Source last checked

26 Oct 2026, 16:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gf8h-gq53-288j

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-62263

Advisory: OpenAM: WebAuthn Java deserialization RCE via ObjectInputFilter depth>1 bypass
IDs: CVE-2026-62263, GHSA-gf8h-gq53-288j
Record: https://patchnext.com/advisories/cve-2026-62263 (revision 1, source checked 26 Oct 2026, 16:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.openidentityplatform.openam:openam-auth-webauthn 16.1.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.openidentityplatform.openam:openam-auth-webauthn: affected <= 16.1.1; fixed in 16.1.2

## Suggested inspection (read-only)
- Maven org.openidentityplatform.openam:openam-auth-webauthn: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.openidentityplatform.openam:openam-auth-webauthn.
- 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-gf8h-gq53-288j (GitHub-reviewed advisory GHSA-gf8h-gq53-288j lists affected ranges: Maven org.openidentityplatform.openam:openam-auth-webauthn >=0 <=16.1.1)

Commands are suggestions: review each one before running it.