CVE-2026-33661
Auth bypass in WeChat Pay callback via Host: localhost
Is CVE-2026-33661 being exploited?
Not confirmed. CVE-2026-33661 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 0.50% probability of exploitation in the next 30 days.
How severe is CVE-2026-33661?
CVE-2026-33661 is rated High with a CVSS score of 8.6. 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-2026-33661?
Yes. A fix has been recorded for CVE-2026-33661. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-33661 affect?
CVE-2026-33661 affects Pay SDK for WeChat Pay integration (versions < 3.7.20), WeChat Pay callback endpoint in PSR-7 apps. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-33661?
Upgrade to 3.7.20+; validate host checks in verify_wechat_sign
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Auth bypass enables forging WeChat Pay notifications; orders could be marked paid without real payment.
Patch when possible
- affected< 3.7.20
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.