CVE-2026-56709

HIGH

7.5

CVSS v3

Description

Grav before 3.9.2 fails to validate untrusted Host headers in the sendInvitationEmail() function when constructing token-bearing invitation links. Attackers can manipulate the Host header to poison invitation links and redirect users to attacker-controlled domains, bypassing the require_trusted_host protection which only covers password reset flows.

CWE-350

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

0.26%probability of exploitation in 30 days

17thpercentile

Low risk: more likely to be exploited than 17% of all known CVEs.

References

Other references2

Related Vulnerabilities

Other CWE-350 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2021-22884	High	7.5	32%	-	Fix
CVE-2018-7160	High	8.8	9.9%	-	Fix
CVE-2017-0902	High	8.1	4.8%	-	Fix
CVE-2026-1490	Critical	9.8	1.2%	-	-
CVE-2021-34561	High	7.5	0.9%	-	-
CVE-2020-11091	Medium	5.8	0.9%	-	Fix

Common questions

How do I fix CVE-2026-56709?

No published fix for CVE-2026-56709 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

Is CVE-2026-56709 being actively exploited?

Not that we know of. CVE-2026-56709 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.26% is the estimated probability that it will be exploited in the next 30 days. That is higher than 17% of all scored CVEs.

How severe is CVE-2026-56709?

CVE-2026-56709 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-26.