CVE-2026-33439CWE-502

Pre-Authentication Remote Code Execution via `jato.clientSession` Deserialization in OpenAM

Critical · published April 7, 2026

CVSS v4.0
9.3
EPSS
8%
Percentile
95.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
9.3 · CRITICAL
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
EPSS
0.08428 · 95.0th percentile
Weakness
CWE-502 · Deserialization of Untrusted Data
Published
2026-04-07T20:46Z
EPSS history
Timeline
  • 07 APR 20:46Z
    Pre-Authentication Remote Code Execution via `jato.clientSession` Deserialization in OpenAM
    cvelistv5