Is CVE-2026-40194 actively exploited?

CVE-2026-40194 has no public evidence of in-the-wild exploitation as of 2026-04-21.

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

CVE-2026-40194 has a CVSS score of 3.7 (LOW severity). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.

How do I patch CVE-2026-40194?

Patch guidance is available from phpseclib security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-40194.

CVE-2026-40194 - remediation guidance & executive summary

Q: Which products are affected by CVE-2026-40194?

3 products: phpseclib phpseclib, phpseclib phpseclib, phpseclib phpseclib.

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.

CVSS Metrics

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack Vector: network
Complexity: high
Privileges: none
User Action: none
Scope: unchanged
Confidentiality: low
Integrity: none
Availability: none
Weaknesses: CWE-208

Metadata

Primary Vendor: PHPSECLIB
Published: 4/10/2026
Last Modified: 4/21/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

phpseclib : phpseclibphpseclib : phpseclibphpseclib : phpseclib

Remediation Guidance

Executive Summary

Cite this page

CVE-2026-40194. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2026-40194

View on NIST NVD

CVE-2026-40194 vulnerability