Is CVE-2026-40194 in the CISA KEV catalog?

No. CVE-2026-40194 is not currently on the CISA Known Exploited Vulnerabilities list.

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

CVE-2026-40194 has a CVSS v3 base score of 3.7 (LOW).

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

CVE-2026-40194 has an EPSS score of 0.33% (25th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40194?

Upgrade php-phpseclib on debian 12 to 2.0.42-1+deb12u4 or later.

CVE & CISA-KEV Catalog

CVE-2026-40194

LOW

3.7

CVSS v3

NVD

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.

CWE-208

How to fix

Remediation Available

php-phpseclibDebian

Fixed in:2.0.42-1+deb12u4CVE-2026-40194

Fixed in:2.0.48-3+deb13u2CVE-2026-40194

Fixed in:2.0.53-1CVE-2026-40194

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Exploit Intelligence

0.33%probability of exploitation in 30 days

25thpercentile

Low risk: more likely to be exploited than 25% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

github.com

Release Notes3

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Markdown

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-08.