Vulnerability · Published Apr 7, 2026 · Assigned by GitHub_M
CVE-2026-33439Pre-Authentication Remote Code Execution via `jato.clientSession` Deserialization in OpenAM
Critical 9.3
In plain English
A critical-severity unsafe deserialization in OpenAM from OpenIdentityPlatform. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 9.3% (higher than 95% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei, public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official description
Open Access Management (OpenAM) is an access management solution. Prior to 16.0.6, OpenIdentityPlatform OpenAM is vulnerable to pre-authentication Remote Code Execution (RCE) via unsafe Java deserialization of the jato.clientSession HTTP parameter. This bypasses the WhitelistObjectInputStream mitigation that was applied to the jato.pageSession parameter after CVE-2021-35464. An unauthenticated attacker can achieve arbitrary command execution on the server by sending a crafted serialized Java object as the jato.clientSession GET/POST parameter to any JATO ViewBean endpoint whose JSP contains <jato:form> tags (e.g., the Password Reset pages). This vulnerability is fixed in 16.0.6.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Maven | org.openidentityplatform.openam:openam | 16.0.6 | GHSA-2cqq-rpvq-g5qj |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| OpenIdentityPlatform | OpenAM | < 16.0.6 |
Weakness: CWE-502 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N