CVE-2021-25641
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.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 21.2%, higher than 98% of all known CVEs. Patch or mitigate before the next change window.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 21.22% probability · 98th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-502
- Affected
- apache/dubbo
- Source
- security@apache.org
EPSS 21.2% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://lists.apache.org/thread.html/r99ef7fa35585d3a68762de07e8d2b2bc48b8fa669a03e8d84b9673f3%40%3Cdev.dubbo.apache.org%3EMailing List, Vendor Advisory
- https://lists.apache.org/thread.html/r99ef7fa35585d3a68762de07e8d2b2bc48b8fa669a03e8d84b9673f3%40%3Cdev.dubbo.apache.org%3EMailing List, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.