CVE-2026-40194

Publication date 10 April 2026

Last updated 28 September 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

3.7 · Low

Score breakdown

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.

Status

Package Ubuntu Release Status
php-phpseclib 26.04 LTS resolute
Fixed 2.0.51-1ubuntu0.1~esm1
25.10 questing Ignored end of life, was needs-triage
24.04 LTS noble
Fixed 2.0.47-1ubuntu0.1~esm1
22.04 LTS jammy
Fixed 2.0.36-1ubuntu0.1~esm3
20.04 LTS focal
Fixed 2.0.23-2ubuntu0.1~esm3
18.04 LTS bionic
Fixed 2.0.9-1ubuntu0.1~esm3
16.04 LTS xenial
Fixed 2.0.1-1ubuntu0.1~esm1
php-phpseclib3 26.04 LTS resolute
Needs evaluation
25.10 questing Ignored end of life, was needs-triage
24.04 LTS noble
Needs evaluation
22.04 LTS jammy
Needs evaluation
phpseclib 26.04 LTS resolute
Needs evaluation
25.10 questing Ignored end of life, was needs-triage
24.04 LTS noble
Needs evaluation
22.04 LTS jammy
Needs evaluation
20.04 LTS focal
Needs evaluation
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial
Needs evaluation

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Severity score breakdown

CVSS version: CVSS v3.0

Base score 3.7 · Low

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

References

Related Ubuntu Security Notices (USN)

    • USN-8830-1
    • phpseclib vulnerabilities
    • 28 September 2026

Other references

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