Vulnerability · Published Aug 27, 2024 · Assigned by wolfSSL
CVE-2024-1544ECDSA nonce bias caused by truncation
Medium 4.1
In plain English
A medium-severity security flaw in wolfSSL from wolfSSL. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Generating the ECDSA nonce k samples a random number r and then truncates this randomness with a modular reduction mod n where n is the order of the elliptic curve. Meaning k = r mod n. The division used during the reduction estimates a factor q_e by dividing the upper two digits (a digit having e.g. a size of 8 byte) of r by the upper digit of n and then decrements q_e in a loop until it has the correct size. Observing the number of times q_e is decremented through a control-flow revealing side-channel reveals a bias in the most significant bits of k. Depending on the curve this is either a negligible bias or a significant bias large enough to reconstruct k with lattice reduction methods. For SECP160R1, e.g., we find a bias of 15 bits.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | wolfssl | no fix listed | DEBIAN-CVE-2024-1544 |
| Debian:13 | wolfssl | 5.7.2-0.1 | DEBIAN-CVE-2024-1544 |
| Ubuntu:22.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2024-1544 |
| Ubuntu:24.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2024-1544 |
| Ubuntu:25.10 | wolfssl | no fix listed | UBUNTU-CVE-2024-1544 |
| Ubuntu:26.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2024-1544 |
| Ubuntu:26.10 | wolfssl | no fix listed | UBUNTU-CVE-2024-1544 |
Affected products (as reported)
Weakness: CWE-203 · Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N