TI-2026-37954 Aliases CVE-2026-52846 GHSA-vcc4-2c75-vc9v

Caddy: stripHTML template function bypass

MEDIUM 53CWE-116Published 2026-06-23 · Updated 2026-06-25

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: High
Impact type: —
Confidentiality · integrity · availability: Low · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, Caddy’s stripHTML template function cannot reliably remove all HTML tags from input strings. Certain malformed HTML, such as <<>img src=x onerror=alert()>, can bypass the tag-stripping logic, potentially leaving dangerous content in the output if it is later rendered as HTML. This may allow client-side XSS in cases where untrusted strings are rendered unsafely. This vulnerability is fixed in 2.11.4.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00248 16th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed caddy (caddyserver): 2.11.4github.com/caddyserver/caddy/v2 (Go): 2.11.4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
caddyserver	caddy	before 2.11.4	2.11.4	Patch available	CNA
—	github.com/caddyserver/caddy/v2 (Go)	before 2.11.4	2.11.4	Patch available	GHSA-vcc4-2c75-vc9v
—	github.com/caddyserver/caddy (Go)	up to 1.0.5	—	No fix listed	GHSA-vcc4-2c75-vc9v

caddy Vendorcaddyserver Affected before 2.11.4 Fixed in 2.11.4 Patch available CNA
github.com/caddyserver/caddy/v2 (Go) Vendor— Affected before 2.11.4 Fixed in 2.11.4 Patch available GHSA-vcc4-2c75-vc9v
github.com/caddyserver/caddy (Go) Vendor— Affected up to 1.0.5 Fixed in — No fix listed GHSA-vcc4-2c75-vc9v

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:caddyserver:caddy::::::::	before 2.11.4	Vulnerable	caddyserver

cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:* Versions before 2.11.4 Vulnerable ·caddyserver

Remediation

Fix · CNA caddy (caddyserver) Fixed in 2.11.4
Fix · GHSA-vcc4-2c75-vc9v github.com/caddyserver/caddy/v2 (Go) Fixed in 2.11.4 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 1 product

Red Hat Hardened Images

Timeline

2026-10-02 Threatist record created from CVE-2026-52846
2026-10-03 Alias added: GHSA-vcc4-2c75-vc9v

References

Exploit 1

https://github.com/caddyserver/caddy/security/advisories/GHSA-vcc4-2c75-vc9v

Other 1

https://github.com/caddyserver/caddy

TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
TI-2026-21978 Improper input validation in caddyserver caddy CVSS 4.0HIGH 8.9
TI-2026-21974 Caddy's mTLS client authentication silently fails open when CA certificate file is missing or malformed CVSS 4.0HIGH 8.8
TI-2026-23680 Improper authentication in caddyserver caddy CVSS 3.1HIGH 8.8
TI-2026-21976 Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass CVSS 4.0HIGH 7.7
TI-2026-21975 Caddy: MatchPath %xx (escaped-path) branch skips case normalization, enabling path-based route/auth bypass CVSS 4.0HIGH 7.7

See all 19 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences