CVE-2023-39533

libp2p nodes vulnerable to attack using large RSA keys

Workarounds

There are no known workarounds

References

The Golang crypto/tls package also had this vulnerability ("verifying certificate chains containing large RSA keys is slow” https://github.com/golang/go/issues/61460)
Fix in golang/go crypto/tls: https://github.com/golang/go/commit/2350afd2e8ab054390e284c95d5b089c142db017
Fix in quic-go https://github.com/quic-go/quic-go/pull/4012

A malicious peer can use large RSA keys to run a resource exhaustion attack & force a node to spend time doing signature verification of the large key. This vulnerability is present in the core/crypto module of go-libp2p and can occur during the Noise handshake and the libp2p x509 extension verification step.
To prevent this attack, go-libp2p now restricts RSA keys to <= 8192 bits.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2023-39533 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.27.8, 0.28.2, 0.29.1); upgrading removes the vulnerable code path.

Kodem intelligence

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Users should upgrade their go-libp2p versions to >=v0.27.8, >= v0.28.2, or >=v0.29.1
To protect your application, it's necessary to update to these patch releases AND to use the updated Go compiler (1.20.7 or 1.19.12, respectively)

1. What is CVE-2023-39533? CVE-2023-39533 is a high-severity allocation of resources without limits or throttling vulnerability in github.com/libp2p/go-libp2p (go), affecting versions < 0.27.8. It is fixed in 0.27.8, 0.28.2, 0.29.1. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2023-39533? CVE-2023-39533 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/libp2p/go-libp2p are affected by CVE-2023-39533? github.com/libp2p/go-libp2p (go) versions < 0.27.8 is affected.
4. Is there a fix for CVE-2023-39533? Yes. CVE-2023-39533 is fixed in 0.27.8, 0.28.2, 0.29.1. Upgrade to this version or later.
5. Is CVE-2023-39533 exploitable, and should I be worried? Whether CVE-2023-39533 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-39533 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-39533?
   • Upgrade github.com/libp2p/go-libp2p to 0.27.8 or later
   • Upgrade github.com/libp2p/go-libp2p to 0.28.2 or later
   • Upgrade github.com/libp2p/go-libp2p to 0.29.1 or later

Other vulnerabilities in github.com/libp2p/go-libp2p