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Case File

CVE-2021-25641

CRITICAL · CVSS 9.8 EPSS 17.67% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-06-01 · Last synced 2026-08-04

CyberRota Analysis

This is a critical severity vulnerability with a CVSS score of 9.8. It affects Apache. Public exploit code or proof-of-concept references have been detected in its references. Its EPSS score suggests a 17.7% probability of exploitation in the next 30 days. It may be remotely exploitable. Exploitation may require the attacker to be authenticated.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-25641
Severity
CRITICAL
CVSS
9.8
EPSS
17.67%
Apache

Original NVD Description

Each Apache Dubbo server will set a serialization id to tell the clients which serialization protocol it is working on. But for Dubbo versions before 2.7.8 or 2.6.9, an attacker can choose which serialization id the Provider will use by tampering with the byte preamble flags, aka, not following the server's instruction. This means that if a weak deserializer such as the Kryo and FST are somehow in code scope (e.g. if Kryo is somehow a part of a dependency), a remote unauthenticated attacker can tell the Provider to use the weak deserializer, and then proceed to exploit it.

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