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Fencer Intel
medium 6.5

CVE-2026-27589 json

Caddy vulnerable to cross-origin config application via local admin API /load (caddy)

published 8mo ago modified 4mo ago also GHSA-879p-475x-rqh2 , GO-2026-4537 , EUVD-2026-8543

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, the local caddy admin API (default listen `127.0.0.1:2019`) exposes a state-changing `POST /load` endpoint that replaces the entire running configuration. When origin enforcement is not enabled (`enforce_origin` not configured), the admin endpoint accepts cross-origin requests (e.g., from attacker-controlled web content in a victim browser) and applies an attacker-supplied JSON config. This can change the admin listener settings and alter HTTP server behavior without user intent. Version 2.11.1 contains a fix for the issue.

Patch / fix

  • go github.com/caddyserver/caddy/v2 2.11.1
  • caddyserver caddy 2.11.1
  • caddy Debian 12 2.6.2-5+deb12u1
  • caddy Debian 13 2.6.2-12+deb13u1
  • caddy Debian 14 2.11.2-1

debian advisories DEBIAN-CVE-2026-27589

  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260226T182644-150000.1.149.1

suse advisories SUSE-SU-2026:0757-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

  • caddy Alpine 3.23 2.11.2-r0
  • caddy Alpine 3.24 2.11.1-r0

alpine advisories ALPINE-CVE-2026-27589

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

Is CVE-2026-27589 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-27589 updated cvss 6.5

github.com/caddyserver/caddy/v2/modules/caddyhttp: Caddy: Unauthorized configuration modification via cross-origin requests to the admin API

  • 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
partial
Assessed
8mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/caddyserver/caddy/security/advisories/GHSA-879p-475x-rqh2 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/user-attachments/files/25079818/poc.zip referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/user-attachments/files/25079820/PR_DESCRIPTION.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
go github.com/caddyserver/caddy/v2
<2.11.1
2.11.1

Affected products

  • caddyserver caddy

Classification

Weakness
  • CWE-352 Cross-Site Request Forgery

References

Sources

Fencer Intel 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.