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Fencer Vulns
high 8.1

CVE-2026-30851 json

Caddy forward_auth copy_headers Does Not Strip Client-Supplied Headers, Allowing Identity Injection and Privilege Escalation

published 2026-03-06 8 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-10176 , GHSA-7r4p-vjf4-gxv4 , GO-2026-4639

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/caddyserver/caddy/v2/modules/caddyhttp/reverseproxy 2.11.2
  • go github.com/caddyserver/caddy/v2 2.11.2
  • caddyserver caddy 2.11.2
  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260317T205859-150000.1.152.1

suse advisories SUSE-SU-2026:1042-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

  • caddy Alpine 3.24, Alpine 3.23 2.11.2-r0

alpine advisories ALPINE-CVE-2026-30851

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-30851 updated cvss 8.1

github.com/caddyserver/caddy/v2/modules/caddyhttp/reverseproxy: Caddy: Privilege escalation via identity injection due to unstripped client headers

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
8 mo ago

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/caddyserver/caddy/security/advisories/GHSA-7r4p-vjf4-gxv4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
GitHub 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
go github.com/caddyserver/caddy/v2/modules/caddyhttp/reverseproxy
>=2.10.0, <2.11.2
2.11.2
go github.com/caddyserver/caddy/v2
>=2.10.0, <2.11.2
2.11.2

Affected products

  • caddyserver caddy

Classification

Weakness
  • CWE-287 Improper Authentication
  • CWE-345 Insufficient Verification of Data Authenticity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.