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CVE-2021-25641

CRITICALCVSS 9.8/10EPSS 17.67%

Last modified

CVE-2021-25641 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 17.67% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
17.67%

96.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
ApacheDubbo>= 2.5.0, < 2.6.9
ApacheDubbo>= 2.7.0, < 2.7.8

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2021-25641?
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.
How severe is CVE-2021-25641?
CVE-2021-25641 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 17.67% probability of exploitation in the next 30 days.
How do I fix CVE-2021-25641?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-25641?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST