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Description

Magento Long Term Support (LTS) is an unofficial, community-driven project provides an alternative to the Magento Community Edition e-commerce platform with a high level of backward compatibility. Prior to 20.18.0, the XML-RPC / SOAP API session ID is generated using an outdated, time-based construction rather than a Cryptographically Secure Pseudo-Random Number Generator (CSPRNG). All inputs to the MD5 hash are time-derived and non-secure. Because the resulting digest relies entirely on the timestamp and the PHP internal LCG state, the effective entropy is severely constrained. This violates the OWASP ASVS v4 requirement of ≥ 64 bits of entropy (V3.2.2) and NIST SP 800-63B standards. By narrowing the LCG window (via server state leaks or general predictability) and leveraging the lack of API rate-limiting, an attacker can generate a localized pool of candidate MD5 hashes and execute a high-speed online brute-force attack to hijack active API sessions. This vulnerability is fixed in 20.18.0.

PUBLISHED Reserved 2026-04-24 | Published 2026-05-15 | Updated 2026-05-15 | Assigner GitHub_M




CRITICAL: 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

Problem types

CWE-330: Use of Insufficiently Random Values

CWE-331: Insufficient Entropy

CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Product status

< 20.18.0
affected

References

github.com/...to-lts/security/advisories/GHSA-2cwr-gcf9-pvxr exploit

github.com/...to-lts/security/advisories/GHSA-2cwr-gcf9-pvxr

cve.org (CVE-2026-42155)

nvd.nist.gov (CVE-2026-42155)

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