CVE-2026-52845
Caddy <2.11.4 header override for PHP behind Caddy.
Is CVE-2026-52845 being exploited?
Not confirmed. CVE-2026-52845 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 0.29% probability of exploitation in the next 30 days.
How severe is CVE-2026-52845?
CVE-2026-52845 is rated High with a CVSS score of 8.1. 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-2026-52845?
Yes. A fix has been recorded for CVE-2026-52845. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-52845 affect?
CVE-2026-52845 affects Caddy < 2.11.4, PHP/FastCGI deployments behind Caddy. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-52845?
Upgrade to 2.11.4+
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker can inject/override identity headers for PHP/FastCGI apps behind Caddy, enabling impersonation or access control bypass.
Patch when possible
- affected< 2.11.4
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.