{"id":"GHSA-p9w4-585h-g3c7","summary":"biscuit-auth vulnerable to public key confusion in third party block","details":"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:\n\n- the public key of the previous block (used in the signature)\n- the public keys part of the token symbol table (for public key interning in datalog expressions)\n\nA third-part block request forged by a malicious user can trick the third-party authority into generating datalog trusting the wrong keypair.\n\nConsider the following example (nominal case)\n\n- Authority `A` emits the following token: `check if thirdparty(\"b\") trusting ${pubkeyB}`\n- The well-behaving holder then generates a third-party block request based on the token and sends it to third-party authority `B`\n- Third-party `B` generates the following third-party block `thirdparty(\"b\"); check if thirdparty(\"c\") trusting ${pubkeyC}`\n- The token holder now must obtain a third-party block from third party `C` to be able to use the token\n\nNow, with a malicious user:\n- Authority `A` emits the following token: `check if thirdparty(\"b\") trusting ${pubkeyB}`\n- The holder then attenuates the token with the following third party block `thirdparty(\"c\")`, signed with a keypair `pubkeyD, privkeyD)` they generate\n- The holder then generates a third-party block request based on this token, but alter the `ThirdPartyBlockRequest` `publicKeys` field and replace `pubkeyD` with `pubkeyC`\n- Third-party `B` generates the following third-party block `thirdparty(\"b\"); check if thirdparty(\"c\") trusting ${pubkeyC}`\n- Due to the altered symbol table, the actual meaning of the block is `thirdparty(\"b\"); check if thirdparty(\"c\") trusting ${pubkeyD}`\n- The attacker can now use the token without obtaining a third-party block from `C`.\n\n### Impact\n\nTokens with third-party blocks containing `trusted` annotations generated through a third party block request\n","aliases":["CVE-2024-41949","CVE-2024-42350","GHSA-47cq-pc2v-3rmp","GHSA-rgqv-mwc3-c78m","HSEC-2024-0009"],"modified":"2025-10-09T14:13:37.207766Z","published":"2024-07-31T21:15:41Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2024-07-31T21:15:41Z","nvd_published_at":"2024-08-01T22:15:28Z","cwe_ids":["CWE-269"],"severity":"LOW"},"references":[{"type":"WEB","url":"https://github.com/biscuit-auth/biscuit-rust/security/advisories/GHSA-p9w4-585h-g3c7"},{"type":"WEB","url":"https://github.com/biscuit-auth/biscuit/security/advisories/GHSA-rgqv-mwc3-c78m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-41949"},{"type":"PACKAGE","url":"https://github.com/biscuit-auth/biscuit-rust"}],"affected":[{"package":{"name":"biscuit-auth","ecosystem":"crates.io","purl":"pkg:cargo/biscuit-auth"},"ranges":[{"type":"SEMVER","events":[{"introduced":"4.0.0"},{"fixed":"5.0.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/07/GHSA-p9w4-585h-g3c7/GHSA-p9w4-585h-g3c7.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:L/A:N"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N"}]}