CVE-2024-9143

What it actually does

Out-of-bounds memory reads or writes triggered by low-level GF(2^m) elliptic curve APIs when supplied untrusted explicit field polynomial values that have a zero constant term, via functions such as EC_GROUP_new_curve_GF2m, EC_GROUP_new_from_params, and BN_GF2m_* helpers.

Why it matters to the business

Applications that rely on exotic explicit binary curve parameters may experience abrupt termination or, in rare cases, remote code execution; standard named-curve or X.509 certificate usage is unaffected, so overall exposure and operational risk remain low but still require patching to eliminate the memory-safety gap.

How an attack unfolds

An attacker identifies an application that accepts or processes custom explicit GF(2^m) curve parameters through the vulnerable low-level APIs, crafts a field polynomial with a zero constant term, and supplies the malformed parameters to trigger out-of-bounds memory access; the resulting corruption may be leveraged for denial of service or, less commonly, code execution, although the attack surface is narrow because common protocols and certificate formats prevent such inputs.

How to fix it

Upgrade OpenSSL to a build that includes commit 72ae83ad214d2eef262461365a1975707f862712; rebuild and redeploy any dependent applications or libraries; avoid use of explicit GF(2^m) curve parameters with untrusted input until the update is applied.

How to confirm the fix worked

Confirm the presence of commit 72ae83ad214d2eef262461365a1975707f862712 in the OpenSSL source tree or verify the resulting library version; exercise any custom curve-handling code paths with both valid and previously problematic polynomial values to ensure no crashes occur.

Typical attack path

1. Locate or coerce an application into using the low-level GF(2^m) curve construction APIs with attacker-controlled parameters
2. Craft an explicit curve definition containing a field polynomial whose constant term is zero
3. Submit the malformed parameters to EC_GROUP_new_curve_GF2m or equivalent
4. Trigger out-of-bounds read or write to induce crash or attempt memory corruption exploitation

How to detect it

Search application and library logs for segmentation faults or memory errors during elliptic-curve initialization; review source code and configuration for any direct calls to the affected low-level GF(2^m) APIs with non-constant or externally supplied polynomials.

What your security team should do

• Inventory all uses of EC_GROUP_new_curve_GF2m, EC_GROUP_new_from_params, and BN_GF2m_* functions
• Apply the fixed commit or newer release in the next maintenance window
• Disable or sandbox any code paths that accept exotic explicit binary curve parameters from external sources
• Update dependency scanners to flag pre-fix OpenSSL versions