Is CVE-2021-25641 actively exploited?

No active exploitation of CVE-2021-25641 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-25641 be exploited remotely?

Yes. CVE-2021-25641 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-25641?

CVE-2021-25641 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2021-25641

CWE-502Published: June 1, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-25641 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-502): Insecure deserialization vulnerabilities allow attackers to inject malicious objects during deserialization, potentially enabling remote code execution.