CVE-2026-55087PoC

LOWCVSS 6.1 · MEDIUM

Exploit discussion active in current signal (1 latest mentions)

Immediate actions

Hunt for exploitation attempts and persistence artifacts
Increase monitoring for publicly documented tradecraft
Track advisory updates for patch or workaround availability

Recommended action window: High priority (within 72h)

NVD description

Etherpad is a real-time collaborative editor. From 2.1.0 until 3.1.0, Etherpad uses the attacker-controlled x-proxy-path request header in src/node/hooks/express/admin.ts when substituting paths into HTML, JavaScript, and CSS under /admin without sanitization, Vary: x-proxy-path, or Cache-Control: private, no-store. A shared proxy or CDN can cache the resulting response and serve attacker-injected script to an administrator. In src/node/hooks/express/specialpages.ts, version 3.0.0 also accepts a protocol-relative x-proxy-path value when constructing the /p/:pad/timeslider redirect, allowing redirection to an attacker-controlled host. The issues are exploitable when the deployment permits client-supplied x-proxy-path headers to reach Etherpad. This issue is fixed in version 3.1.0.

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1.5/ 10 priority

Sources & remediation

Other references

Weakness type (CWE)

CWE-79CWE-444CWE-601

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

NONE

Momentum

NONE

Threat summary

Public PoC is present in monitored signal
1 mentions across 1 observed day

What's happening

PoC mentioned or linked in 1 signal
Technical details provided in 1 signal
1 total mentions across 1 day

Deep dive

Activity timeline1 mentions / 1d

Signal classification1 categories

PoC

1100.0%

Referenced assets1 URL

By indicator

https://cloud.projectdiscovery.io/library/CVE-2026-55087

Full discourse1 post

pdnuclei-bot@pdnuclei_bot46d
PoC
🚨 CVE-2026-55087 - medium 🚨 Etherpad 2.1.0 <= 3.0.0 - Cross-Site Scripting > Etherpad versions 2.1.0 through 3.0.0 reflect the x-proxy-path request header into ad... 👾 https://cloud.projectdiscovery.io/library/CVE-2026-55087 @pdnuclei #NucleiTemplates #cve
Post summary
A medium‑severity XSS flaw in Etherpad 2.1.0‑3.0.0 is noted, with a link to a Project Discovery Nuclei template that likely contains a PoC; no exploitation or patch information is provided.
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