CVE-2021-25641
Dubbo Zookeeper does not check serialization id
- Published
- May 29, 2021
- Updated
- Aug 3, 2024
- Assigning CNA
- apache
- Evidence observed
- Aug 8, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HModerate · next 30 days
- Percentile
- 97.5%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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.
Sources
2Apache/Alibaba Dubbo <= 2.7.3 PoC Code for CVE-2021-25641 RCE via Deserialization of Untrusted Data; Affects Versions <= 2.7.6 With Different Gadgets
- CVE-2021-25641Exploit
Exploit for CVE-2021-25641 targeting Apache Dubbo RCE vulnerability in versions 2.5.x to 2.7.8. Packaged standalone JAR for direct deployment against vulnerable Dubbo services.
Responsible use
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