CVE-2026-77806
Unauthenticated RCE in SPIP via mishandled X-Spip-Filtre header
Is CVE-2026-77806 being exploited?
Not confirmed. CVE-2026-77806 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 4.2% probability of exploitation in the next 30 days.
How severe is CVE-2026-77806?
CVE-2026-77806 is rated Critical with a CVSS score of 9.8. 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-2026-77806?
Yes. A fix has been recorded for CVE-2026-77806. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-77806 affect?
CVE-2026-77806 affects SPIP CMS < 4.4.21 (analyse_resultat_skel code path). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-77806?
Update SPIP to 4.4.21+, block X-Spip-Filtre header via WAF, isolate unpatched hosts
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote code execution via crafted X-Spip-Filtre header; can lead to full server compromise, data theft, or malware deployment.
Immediate action required
- affected< 4.4.21
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.