CVE-2026-40194
Low
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.
SeverityLow
CVSS3.7
Exploit probability—
ProductPhpseclib
PublishedApr 10, 2026
First seenApr 10, 2026
Weakness typeCWE-208CWE-208
How to fix
Update
- phpseclib phpseclib2.0.53, 3.0.51 or later
- phpseclib/phpseclib1.0.28, 2.0.53, 3.0.51 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| phpseclib phpseclib | v ≤ 1.0.27, 2.0.0 ≤ v < 2.0.53, 3.0.0 ≤ v < 3.0.51 | 2.0.53, 3.0.51 |
| phpseclib/phpseclibPackagist | 0.1.1 ≤ v < 1.0.28, 2.0.0 ≤ v < 2.0.53, 3.0.0 ≤ v < 3.0.51 | 1.0.28, 2.0.53, 3.0.51 |
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