How severe is GHSA-879p-475x-rqh2?

No CVSS score has been assigned to GHSA-879p-475x-rqh2 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-879p-475x-rqh2?

GHSA-879p-475x-rqh2 affects the following packages: github.com/caddyserver/caddy/v2 (Go). Ecosystems affected: Go.

How do I fix GHSA-879p-475x-rqh2?

Update github.com/caddyserver/caddy/v2 to 2.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-879p-475x-rqh2 is resolved across your whole dependency graph.

How do I detect GHSA-879p-475x-rqh2 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/caddyserver/caddy/v2. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-879p-475x-rqh2 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-879p-475x-rqh2?

O3 pinpoints whether GHSA-879p-475x-rqh2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-879p-475x-rqh2 actively exploited in the wild?

No public exploit code has been indexed for GHSA-879p-475x-rqh2 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-879p-475x-rqh2?

GHSA-879p-475x-rqh2 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 6th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was GHSA-879p-475x-rqh2 published, and has it been updated?

GHSA-879p-475x-rqh2 was published on February 24, 2026 and was last updated on February 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-879p-475x-rqh2

Caddy is vulnerable to cross-origin config application via local admin API /load

Also known asCVE-2026-27589GO-2026-4537

Published

Feb 24, 2026

Updated

Feb 27, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk6th percentile+0.14%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐹github.com/caddyserver/caddy/v2

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

commit: e0f8d9b2047af417d8faf354b675941f3dac9891 (as-of 2026-02-04) channel: GitHub security advisory (per SECURITY.md)

summary

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.

Severity

Medium

Justification:

The attacker can apply an arbitrary caddy config (integrity impact) by driving a victim’s local admin API.
Exploitation requires a victim running caddy with the admin API enabled and visiting an attacker-controlled page (or otherwise issuing the request from an untrusted local client).

Affected component

caddyconfig/load.go: adminLoad.handleLoad (/load admin endpoint)
Pinned callsite: https://github.com/caddyserver/caddy/blob/e0f8d9b2047af417d8faf354b675941f3dac9891/caddyconfig/load.go#L73

Reproduction

Attachment: poc.zip (integration harness) with canonical and control runs.

unzip -q -o poc.zip -d poc
cd poc/poc-F-CADDY-ADMIN-LOAD-001
make test

Expected output (excerpt):

[CALLSITE_HIT]: adminLoad.handleLoad
[PROOF_MARKER]: http_code=200 admin_moved=true response_pwned=true

Control output (excerpt):

[NC_MARKER]: http_code=403 load_blocked=true admin_moved=false response_pwned=false

Impact

An attacker can replace the running caddy configuration via the local admin API. Depending on the deployed configuration/modules, this can:

Change admin listener settings (e.g., move the admin listener to a new address)
Change HTTP server behavior (e.g., alter routes/responses)

Suggested remediation

Ensure cross-origin web content cannot trigger POST /load on the local admin API by default, for example by:

Enabling origin enforcement by default for unsafe methods, and/or
Requiring an unguessable token for /load (and other state-changing admin endpoints).

poc.zip PR_DESCRIPTION.md

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/caddyserver/caddy/v2`	all versions	2.11.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/caddyserver/caddy/v2. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/caddyserver/caddy/v2 to 2.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-879p-475x-rqh2 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-879p-475x-rqh2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-879p-475x-rqh2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

commit: e0f8d9b2047af417d8faf354b675941f3dac9891 (as-of 2026-02-04) channel: GitHub security advisory (per SECURITY.md) ## summary 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 wi

O3 Security · Impact-Aware SCA

Is GHSA-879p-475x-rqh2 in your dependencies?

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