{"id":"CVE-2026-42155","aliases":["GHSA-2cwr-gcf9-pvxr"],"url":"https://o3.security/vulnerability/CVE-2026-42155","summary":"Magento LTS: Weak API Session ID — Predictable MD5 of Time-Derived Inputs","details":"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 Prior to 20.18.0, the XML-RPC / SOAP API session ID is generated using an outdated, time-based construction rather than a Cryptographically Secure Pseudo-Random Number Generator (CSPRNG).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":"2026-05-15T17:05:02.436Z","modified":"2026-08-07T11:31:33.290316877Z","cvss":null,"epss":{"score":0.00267,"percentile":0.18642,"asOf":"2026-08-08"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"openmage/magento-lts","fixedVersion":"20.18.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42155.json"},{"type":"ADVISORY","url":"https://github.com/OpenMage/magento-lts/security/advisories/GHSA-2cwr-gcf9-pvxr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42155"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:31:33.290316877Z"}}