Summary
biscuit-java vulnerable to public key confusion in third party block
Description
Third-party blocks can be generated without transferring the whole token to the third-party authority. Instead, a ThirdPartyBlock request can be sent, providing only the necessary info to generate a third-party block and to sign it:
the public key of the previous block (used in the signature)
the public keys part of the token symbol table (for public key interning in datalog expressions)
A third-part block request forged by a malicious user can trick the third-party authority into generating datalog trusting the wrong keypair.
Consider the following example (nominal case)
- Authority A emits the following token:
check if thirdparty("b") trusting ${pubkeyB} - The well-behaving holder then generates a third-party block request based on the token and sends it to third-party authority B
- Third-party B generates the following third-party block
thirdparty("b"); check if thirdparty("c") trusting ${pubkeyC} - The token holder now must obtain a third-party block from third party C to be able to use the token
Now, with a malicious user:
- Authority A emits the following token:
check if thirdparty("b") trusting ${pubkeyB} - The holder then attenuates the token with the following third party block
thirdparty("c"), signed with a keypair pubkeyD, privkeyD) they generate - The holder then generates a third-party block request based on this token, but alter the
ThirdPartyBlockRequestpublicKeys field and replace pubkeyD with pubkeyC - Third-party B generates the following third-party block
thirdparty("b"); check if thirdparty("c") trusting ${pubkeyC} - Due to the altered symbol table, the actual meaning of the block is
thirdparty("b"); check if thirdparty("c") trusting ${pubkeyD} - The attacker can now use the token without obtaining a third-party block from C.
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
References
Are there any links users can visit to find out more?
Impact
Tokens with third-party blocks containing trusted annotations generated through a third party block request. Due to implementation issues in biscuit-java, third party block support in published versions is inoperating. Nevertheless, to synchronize with other implementations, we publish this advisory and the related fix.
CVE-2024-41948 has a CVSS score of 3.0 (Medium). The vector is network-reachable, high 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 (4.0.0); 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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Has the problem been patched? What versions should users upgrade to?
Frequently Asked Questions
- What is CVE-2024-41948? CVE-2024-41948 is a medium-severity security vulnerability in org.biscuitsec:biscuit (maven), affecting versions >= 3.0.0, < 4.0.0. It is fixed in 4.0.0.
- How severe is CVE-2024-41948? CVE-2024-41948 has a CVSS score of 3.0 (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 org.biscuitsec:biscuit are affected by CVE-2024-41948? org.biscuitsec:biscuit (maven) versions >= 3.0.0, < 4.0.0 is affected.
- Is there a fix for CVE-2024-41948? Yes. CVE-2024-41948 is fixed in 4.0.0. Upgrade to this version or later.
- Is CVE-2024-41948 exploitable, and should I be worried? Whether CVE-2024-41948 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-2024-41948 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-2024-41948? Upgrade
org.biscuitsec:biscuitto 4.0.0 or later.