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Php phpseclib: 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… (CVE-2026-40194)

0
Medium
VulnerabilityCVE-2026-40194gcveosvubuntu-cve-2026-40194cve-2026-40194ubuntu-pro-16-04-ltsubuntu-pro-18-04-ltsubuntu-pro-20-04-ltsubuntu-pro-22-04-ltsubuntu-24-04-ltsubuntu-pro-24-04-ltsubuntu-25-10ubuntu-26-04-ltsubuntu-pro-26-04-lts
Published: 04/10/2026 (04/10/2026, 21:16:00 UTC)
Source: GCVE Database
Product: php-phpseclib

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.

CVSS v3.1

Score 3.7low

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected software

Ubuntu:Pro:16.04:LTSmore threats →ghsa
php-phpseclib
pkg:deb/ubuntu/php-phpseclib?arch=source&distro=esm-apps-legacy/xenial
Affected versions
<2.0.1-1ubuntu0.1~esm1=2.0.1-1=2.0.1-1build1
Ubuntu:Pro:16.04:LTSmore threats →ghsa
phpseclib
pkg:deb/ubuntu/phpseclib?arch=source&distro=esm-apps-legacy/xenial
Affected versions
=0.3.10-3=1.0.0-2=1.0.0-3=1.0.1-1=1.0.1-3=1.0.1-3ubuntu0.1=1.0.1-3ubuntu0.1+esm1
Ubuntu:Pro:18.04:LTSmore threats →ghsa
php-phpseclib
pkg:deb/ubuntu/php-phpseclib?arch=source&distro=esm-apps/bionic
Affected versions
<2.0.9-1ubuntu0.1~esm3=2.0.6-1=2.0.7-1=2.0.9-1=2.0.9-1ubuntu0.1~esm2
Ubuntu:Pro:18.04:LTSmore threats →ghsa
phpseclib
pkg:deb/ubuntu/phpseclib?arch=source&distro=esm-apps/bionic
Affected versions
=1.0.7-1=1.0.8-1=1.0.9-1=1.0.9-1ubuntu0.1~esm1=1.0.9-1ubuntu0.1~esm2
Ubuntu:Pro:20.04:LTSmore threats →ghsa
php-phpseclib
pkg:deb/ubuntu/php-phpseclib?arch=source&distro=esm-apps/focal
Affected versions
<2.0.23-2ubuntu0.1~esm3=2.0.21-2=2.0.23-2=2.0.23-2ubuntu0.1~esm2
Ubuntu:Pro:20.04:LTSmore threats →ghsa
phpseclib
pkg:deb/ubuntu/phpseclib?arch=source&distro=esm-apps/focal
Affected versions
=1.0.16-2=1.0.18-2=1.0.18-2ubuntu0.1~esm1=1.0.18-2ubuntu0.1~esm2
Ubuntu:Pro:22.04:LTSmore threats →ghsa
php-phpseclib
pkg:deb/ubuntu/php-phpseclib?arch=source&distro=esm-apps/jammy
Affected versions
<2.0.36-1ubuntu0.1~esm3=2.0.30-2ubuntu1=2.0.34-1=2.0.35-1=2.0.36-1=2.0.36-1ubuntu0.1~esm2
Ubuntu:Pro:22.04:LTSmore threats →ghsa
php-phpseclib3
pkg:deb/ubuntu/php-phpseclib3?arch=source&distro=esm-apps/jammy
Affected versions
=3.0.9-1=3.0.10-1=3.0.12-2=3.0.13-1=3.0.13-1ubuntu0.1~esm1
Ubuntu:Pro:22.04:LTSmore threats →ghsa
phpseclib
pkg:deb/ubuntu/phpseclib?arch=source&distro=esm-apps/jammy
Affected versions
=1.0.19-3ubuntu2=1.0.19-3ubuntu3=1.0.20-1=1.0.20-1ubuntu0.1~esm1
Ubuntu:24.04:LTSmore threats →ghsa
php-phpseclib3
pkg:deb/ubuntu/php-phpseclib3?arch=source&distro=noble
Affected versions
=3.0.21-2=3.0.33-1=3.0.34-1=3.0.35-1=3.0.37-1
Ubuntu:Pro:24.04:LTSmore threats →ghsa
php-phpseclib
pkg:deb/ubuntu/php-phpseclib?arch=source&distro=esm-apps/noble
Affected versions
<2.0.47-1ubuntu0.1~esm1=2.0.44-1=2.0.45-1=2.0.46-1=2.0.47-1
Ubuntu:Pro:24.04:LTSmore threats →ghsa
phpseclib
pkg:deb/ubuntu/phpseclib?arch=source&distro=esm-apps/noble
Affected versions
=1.0.21-2=1.0.22-1=1.0.23-1=1.0.23-1ubuntu0.1~esm1
Ubuntu:25.10more threats →ghsa
php-phpseclib
pkg:deb/ubuntu/php-phpseclib?arch=source&distro=questing
Affected versions
=2.0.48-3
Ubuntu:25.10more threats →ghsa
php-phpseclib3
pkg:deb/ubuntu/php-phpseclib3?arch=source&distro=questing
Affected versions
=3.0.43-2
Ubuntu:25.10more threats →ghsa
phpseclib
pkg:deb/ubuntu/phpseclib?arch=source&distro=questing
Affected versions
=1.0.23-6
Ubuntu:26.04:LTSmore threats →ghsa
php-phpseclib3
pkg:deb/ubuntu/php-phpseclib3?arch=source&distro=resolute
Affected versions
=3.0.43-2=3.0.44-1=3.0.47-1=3.0.49-1=3.0.49-1ubuntu1
Ubuntu:Pro:26.04:LTSmore threats →ghsa
php-phpseclib
pkg:deb/ubuntu/php-phpseclib?arch=source&distro=esm-apps/resolute
Affected versions
<2.0.51-1ubuntu0.1~esm1=2.0.48-3=2.0.49-1=2.0.51-1
Ubuntu:Pro:26.04:LTSmore threats →ghsa
phpseclib
pkg:deb/ubuntu/phpseclib?arch=source&distro=esm-apps/resolute
Affected versions
=1.0.23-6=1.0.24-1=1.0.24-1ubuntu0.1~esm1

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

Technical Details

Gcve Source
db.gcve.eu
Osv Id
UBUNTU-CVE-2026-40194
Osv Schema Version
1.7.0
Ecosystems
["Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:Pro:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:Pro:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS","Ubuntu:Pro:26.04:LTS"]
Cvss Version
3.1

Patch Information

Threat ID: 6abb4194f7a7c54106cc380e

Added to database: 09/29/2026, 04:41:56 UTC

Last updated: 09/29/2026, 04:41:56 UTC

Views: 1

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