CVE-2026-71253 Apache Johnzon - Unsafe Reflection

Apache Johnzon 1.0.0 before 2.2.0 contains an unsafe reflection vulnerability caused by ClassConverter loading and static-initializing attacker-named classes from untrusted JSON, letting attackers execute arbitrary code remotely, exploit requires crafted JSON input.

CVSS base score 9.8 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.36% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Unsafe Reflection
Impact
Remote Code Execution
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
19 October 2026
Updated
21 October 2026
Weakness
CWE-470

Vendor fix

Upgrade to version 1.3.1 (javax namespace) or 2.2.0 (jakarta specification namespace).

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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