{"id":"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 Prior to 20.18.0, the XML-RPC / SOAP API session ID is generated using an outdated, time-based construction rather than a Cryptographically Secure Pseudo-Random Number Generator (CSPRNG).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.","aliases":["GHSA-2cwr-gcf9-pvxr"],"modified":"2026-08-12T03:51:22.665965102Z","published":"2026-05-15T17:05:02.436Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-330","CWE-331","CWE-338"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42155.json"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/openmage/magento-lts","events":[{"introduced":"0"},{"fixed":"c565e96cc893b08fe9ae8e4efe4f5f26055fc57d"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"fixed":"20.18.0"}]}}],"versions":["v20.17.0","v20.16.0","v20.15.0","v20.14.0","v20.13.0","v20.12.2","v20.12.1","v20.12.0","v20.11.0","v20.10.1","v21.0.0-beta2","v20.10.0","v20.9.0","v20.8.0","v20.7.0","v20.6.0","v20.5.0","v20.4.0","v20.3.0","v20.2.0","v20.1.1","v20.1.0","v20.1.0-rc7","v20.1.0-rc6","v20.1.0-rc5","v20.1.0-rc4","v20.1.0-rc3","v20.1.0-rc2","v20.1.0-rc1","v20.0.18","v20.0.17","v20.0.16","v20.0.15","v20.0.13","v20.0.12","v20.0.11","v20.0.10","v20.0.8","v20.0.7","v20.0.6","v20.0.5","v20.0.4","v20.0.3","v20.0.2","v20.0.1","v20.0.0","v19.4.4","v19.4.3","v19.4.2","v19.4.1","v19.4.0","1.9.0.1","1.9.1.1","1.9.1.0-lts","1.9.0.0","1.8.1.0","1.7.0.2","1.7.0.1","1.7.0.0","1.6.1.0","1.6.0.0","1.6.0.0-rc2","1.6.0.0-rc1","1.6.0.0-beta1","1.6.0.0-alpha1","1.5.1.0","1.5.0.1","1.5.0.0","1.5.0.0-rc2","1.5.0.0-rc1","1.5.0.0-beta2","1.5.0.0-beta1","1.5.0.0-alpha2","1.5.0.0-alpha1","1.4.2.0","1.4.1.1","1.4.1.0","1.4.0.1","1.3.2.4","1.4.0.0","1.4.0.0-rc1","1.4.0.0-beta1","1.4.0.0-alpha3","1.4.0.0-alpha2","1.4.0.0-alpha1","1.3.2.3","1.3.2.2","1.3.2.1","1.3.2","1.3.1.1","1.3.1","1.3.0","1.2.1.2","1.2.1","1.2.0.3","1.2.0.2","1.2.0.1","1.2.0","1.1.8","1.1.7","1.1.6","1.1.5","1.1.4","1.1.3","1.1.2","1.1.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42155.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N"}]}