How severe is CVE-2026-30851?

CVE-2026-30851 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-30851 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-30851?

CVE-2026-30851 affects Caddyserver Caddy. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-30851?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-30851 have an EU (EUVD) identifier?

Yes. CVE-2026-30851 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10176.

When was CVE-2026-30851 published?

CVE-2026-30851 was published on 2026-03-07 and last updated on 2026-06-17.

CVE-2026-30851

CVE-2026-30851 is a high-severity vulnerability in Caddyserver Caddy with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-10176
Weakness: CWE-287
Affected product: Caddyserver Caddy
Published: 2026-03-07
Last modified: 2026-06-17

Description

Caddy is an extensible server platform that uses TLS by default. From version 2.10.0 to before version 2.11.2, forward_auth copy_headers does not strip client-supplied headers, allowing identity injection and privilege escalation. This issue has been patched in version 2.11.2.

Frequently asked questions

What is CVE-2026-30851?: Caddy is an extensible server platform that uses TLS by default. From version 2.10.0 to before version 2.11.2, forward_auth copy_headers does not strip client-supplied headers, allowing identity injection and privilege escalation. This issue has been patched in version 2.11.2.
How severe is CVE-2026-30851?: CVE-2026-30851 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-30851 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-30851?: CVE-2026-30851 affects Caddyserver Caddy. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-30851?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-30851 have an EU (EUVD) identifier?: Yes. CVE-2026-30851 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10176.
When was CVE-2026-30851 published?: CVE-2026-30851 was published on 2026-03-07 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*

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