CVE-2026-42155
Magento LTS API session hijack via weak MD5 before 20.18.0
Is CVE-2026-42155 being exploited?
Not confirmed. CVE-2026-42155 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.30% probability of exploitation in the next 30 days.
How severe is CVE-2026-42155?
CVE-2026-42155 is rated Critical with a CVSS score of 9.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-42155?
Yes. A fix has been recorded for CVE-2026-42155. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-42155 affect?
CVE-2026-42155 affects Magento LTS (community) API: XML-RPC/SOAP (pre-20.18.0). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-42155?
Upgrade to 20.18.0+; enforce strong session controls
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker can impersonate API users by brute-forcing time-derived MD5 session IDs; potential admin access.
Patch when possible
- affected< 20.18.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.