Is CVE-2026-40194 actively exploited?

A proof-of-concept exploit is publicly available for CVE-2026-40194, but active exploitation has not been confirmed.

Can CVE-2026-40194 be exploited remotely?

Yes. CVE-2026-40194 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-40194?

CVE-2026-40194 has a CVSS score of 3.7 (LOW).

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LOWPOC

CVE-2026-40194

CWE-208Published: April 10, 2026· Updated: Apr 13, 2026

3.7

CVSS v3.1

Official Description

phpseclib is a PHP secure communications library. Prior to 3.0.51, 2.0.53, and 1.0.28, phpseclib\Net\SSH2::get_binary_packet() uses PHP's != operator to compare a received SSH packet HMAC against the locally computed HMAC. != on equal-length binary strings in PHP uses memcmp(), which short-circuits on the first differing byte. This is a real variable-time comparison (CWE-208), proven by scaling benchmarks. This vulnerability is fixed in 3.0.51, 2.0.53, and 1.0.28.

NVD Source

Technical Analysis

CVE-2026-40194 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A proof-of-concept (PoC) exploit exists for CVE-2026-40194. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.