CVE-2025-27587

What it actually does

Side-channel timing attack on PowerPC allowing extraction of ECDSA nonce K from EVP_DigestSign operations on P-364 curve by correlating signing duration with nonce bit length, enabling private key recovery.

Why it matters to the business

Potential exposure of signing private keys on PowerPC systems using affected cryptographic libraries, though limited to co-located attacker processes and disputed as outside standard threat models, with low overall risk to operations or data confidentiality.

How an attack unfolds

An attacker running on the same physical PowerPC system measures timing of random message signatures via EVP_DigestSign, statistically correlates shorter nonces with faster times to recover K values, then reconstructs the private key; the CVE is disputed as OpenSSL excludes same-system side channels from its threat model and the signal is too weak for practical remote use.

How to fix it

Upgrade blueman on Mageia 5 to version 2.0.3-1.mga5; for OpenSSL components ensure versions beyond 3.3.2 are used on PowerPC where applicable and review any local cryptographic policy exceptions.

How to confirm the fix worked

Confirm blueman package version is at or above 2.0.3-1.mga5 via package manager; test that EVP_DigestSign timing variance no longer correlates with nonce size under controlled local benchmarks.

Typical attack path

1. Gain execution on the same physical PowerPC host as the target process
2. Invoke EVP_DigestSign repeatedly with random messages and record precise signing times
3. Analyze timing data against nonce bit lengths using statistical tests to extract K
4. Use recovered nonces to compute the ECDSA private key

How to detect it

Examine process execution logs and timing telemetry on PowerPC hosts for repeated local calls to signing APIs from untrusted processes; no remote network indicators exist due to the same-system requirement.

What your security team should do

• Apply the listed package upgrade immediately on any PowerPC systems running the affected blueman version
• Review and enforce isolation policies preventing untrusted code from sharing physical hosts with signing workloads
• Monitor EPSS trend for any increase and reassess if new local-attack tooling emerges