{"id":"CVE-2024-58262","aliases":["GHSA-x4gp-pqpj-f43q","RUSTSEC-2024-0344"],"url":"https://o3.security/vulnerability/CVE-2024-58262","summary":"curve25519-dalek has timing variability in `curve25519-dalek`'s `Scalar29::sub`/`Scalar52::sub`","details":"Timing variability of any kind is problematic when working with  potentially secret values such as elliptic curve scalars, and such issues can potentially leak private keys and other secrets. Such a problem was recently discovered in `curve25519-dalek`.\n\nThe `Scalar29::sub` (32-bit) and `Scalar52::sub` (64-bit) functions contained usage of a mask value inside a loop where LLVM saw an opportunity to insert a branch instruction (`jns` on x86) to conditionally bypass this code section when the mask value is set to zero as can be seen in godbolt:\n\n- 32-bit (see L106): https://godbolt.org/z/zvaWxzvqv\n- 64-bit (see L48): https://godbolt.org/z/PczYj7Pda\n\nA similar problem was recently discovered in the Kyber reference implementation:\n\nhttps://groups.google.com/a/list.nist.gov/g/pqc-forum/c/hqbtIGFKIpU/m/cnE3pbueBgAJ\n\nAs discussed on that thread, one portable solution, which is also used in this PR, is to introduce a volatile read as an optimization barrier, which prevents the compiler from optimizing it away.\n\nThe fix can be validated in godbolt here:\n\n- 32-bit: https://godbolt.org/z/jc9j7eb8E\n- 64-bit: https://godbolt.org/z/x8d46Yfah\n\nThe problem was discovered and the solution independently verified by Alexander Wagner <alexander.wagner@aisec.fraunhofer.de> and Lea Themint <lea.thiemt@tum.de> using their DATA tool:\n\nhttps://github.com/Fraunhofer-AISEC/DATA","published":"2025-07-27T20:15:25.057Z","modified":"2026-04-10T05:19:10.178882Z","cvss":{"score":5.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"curve25519-dalek","fixedVersion":"4.1.3"}],"fix":{"url":"https://github.com/dalek-cryptography/curve25519-dalek/pull/659","label":"dalek-cryptography/curve25519-dalek#659"},"references":[{"type":"WEB","url":"https://crates.io/crates/curve25519-dalek"},{"type":"ADVISORY","url":"https://rustsec.org/advisories/RUSTSEC-2024-0344.html"},{"type":"FIX","url":"https://github.com/dalek-cryptography/curve25519-dalek/pull/659"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-58262"},{"type":"WEB","url":"https://github.com/dalek-cryptography/curve25519-dalek/commit/415892acf1cdf9161bd6a4c99bc2f4cb8fae5e6a"},{"type":"PACKAGE","url":"https://github.com/dalek-cryptography/curve25519-dalek"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-04-10T05:19:10.178882Z"}}