What’s Vulnerable › Vulnerabilities

CVE-2024-27354: phpseclib: guardrails needed on isPrime and randomPrime

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-03-01 · updated 2026-06-17
• Weakness: CWE-400

Description

An issue was discovered in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36. An attacker can construct a malformed certificate containing an extremely large prime to cause a denial of service (CPU consumption for an isPrime primality check). NOTE: this issue was introduced when attempting to fix CVE-2023-27560.

Affected products

• Debian Linux: 10.0
• phpseclib: from 1.0.0 before 1.0.23; from 2.0.0 before 2.0.47; from 3.0.0 before 3.0.36 — fixed in 1.0.23, 2.0.47, 3.0.36
• Packagist Phpseclib/Phpseclib: from 0.1.1 before 1.0.23; from 2.0.0 before 2.0.47; from 3.0.0 before 3.0.36; 0.3.0, 0.3.1, 0.3.10, 0.3.5, 0.3.6, 0.3.7 (+99) — fixed in 1.0.23, 2.0.47, 3.0.36

How to fix

Upgrade to a fixed version: phpseclib 1.0.23, 2.0.47, 3.0.36; Packagist Phpseclib/Phpseclib 1.0.23, 2.0.47, 3.0.36. Check the vendor advisory for mitigations.

References

• https://gist.github.com/katzj/ee72f3c2a00590812b2ea3c0c8890e0b
• https://github.com/phpseclib/phpseclib/blob/master/phpseclib/Math/PrimeField.php#L49
• https://lists.debian.org/debian-lts-announce/2024/03/msg00002.html
• https://lists.debian.org/debian-lts-announce/2024/03/msg00003.html
• https://gist.github.com/katzj/ee72f3c2a00590812b2ea3c0c8890e0b
• https://github.com/phpseclib/phpseclib/blob/master/phpseclib/Math/PrimeField.php#L49
• https://lists.debian.org/debian-lts-announce/2024/03/msg00002.html
• https://lists.debian.org/debian-lts-announce/2024/03/msg00003.html

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