Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-40194

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
10/04/2026
Last modified:
08/05/2026

Description

phpseclib is a PHP secure communications library. Starting in 0.1.1 and 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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N CVSS v3.1 Severity and Metrics:

Base Score: 3.70 LOW
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): Low
Integrity (I): None
Availability (A): None

Base Score 3.x
3.70
Severity 3.x
LOW

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:phpseclib:phpseclib:*:*:*:*:*:*:*:* 1.0.27 (including)
cpe:2.3:a:phpseclib:phpseclib:*:*:*:*:*:*:*:* 2.0.0 (including) 2.0.53 (excluding)
cpe:2.3:a:phpseclib:phpseclib:*:*:*:*:*:*:*:* 3.0.0 (including) 3.0.51 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools