Summary
Sequential calls of encryption API (encrypt, wrap, and dump) result in nonce reuse
Problem: Trying to create a new encrypted message with the same cocoon object generates the same ciphertext. It mostly affects MiniCocoon and Cocoon objects with custom seeds and RNGs (where StdRng is used under the hood).
Note: The issue does NOT affect objects created with Cocoon::new which utilizes ThreadRng.
Cause: StdRng produces the same nonce because StdRng::clone resets its state.
Measure: Make encryption API mutable (encrypt, wrap, and dump).
Workaround: Create a new cocoon object with a new seed per each encryption.
How to Reproduce
let cocoon = MiniCocoon::from_password(b"password", &[1; 32]);
let mut data1 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data1)?;
let mut data2 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data2)?;
// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]
// data2: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]
Workaround
For cocoon <= 0.3.3, create a new cocoon with a different seed per each encrypt/wrap/dump call.
let cocoon = MiniCocoon::from_password(b"password", &[1; 32]);
let mut data1 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data1)?;
// Another seed: &[2; 32].
let cocoon = MiniCocoon::from_password(b"password", &[2; 32]);
let mut data2 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data2)?;
// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]
// data2: [53, 223, 209, 96, 130, 99, 209, 108, 83, 189, 123, 81, 19, 1]
Impact
CVE-2024-21530 has a CVSS score of 4.5 (Medium). The vector is requires local access, 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 (0.4.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2024-21530? CVE-2024-21530 is a medium-severity security vulnerability in cocoon (rust), affecting versions < 0.4.0. It is fixed in 0.4.0.
- How severe is CVE-2024-21530? CVE-2024-21530 has a CVSS score of 4.5 (Medium). 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.
- Which versions of cocoon are affected by CVE-2024-21530? cocoon (rust) versions < 0.4.0 is affected.
- Is there a fix for CVE-2024-21530? Yes. CVE-2024-21530 is fixed in 0.4.0. Upgrade to this version or later.
- Is CVE-2024-21530 exploitable, and should I be worried? Whether CVE-2024-21530 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
- What actually determines whether CVE-2024-21530 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.
- How do I fix CVE-2024-21530? Upgrade
cocoonto 0.4.0 or later.