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CVE-2026-55086 medium CVSS 4.2

Vulnerability in ep_etherpad-lite (CVE-2026-55086)

Summary

Vulnerability in ep_etherpad-lite (CVE-2026-55086). Risk of unauthorized operations or information disclosure. Exploitable via ExportHandler. Mitigation: upgrade to 3.1.0 or later.

Original description

The description as published by the source.

Description

src/node/handler/ImportHandler.ts and src/node/handler/ExportHandler.ts both compute their temporary working-file paths as:

const randNum = Math.floor(Math.random() * 0xFFFFFFFF);
const srcFile = `${os.tmpdir()}/etherpad_export_${randNum}.html`;
const destFile = `${os.tmpdir()}/etherpad_export_${randNum}.${type}`;

Two flaws compound:

  1. Math.random() is not crypto-secure. It yields at most ~32 bits of entropy and is predictable across calls within the same Node process (V8 shares PRNG state between consecutive Math.random() invocations). An attacker on the same host who observes any earlier temp-file name from logs or other side channels can predict subsequent names.

  2. The paths land in os.tmpdir(). On a typical Linux system this is /tmp — a shared world-writable directory. An unprivileged local attacker can pre-create a symbolic link at a predicted path pointing at any file the Etherpad process can write:

    ln -s /etc/etherpad/SESSIONKEY.txt /tmp/etherpad_export_.html

    When ExportHandler calls fs.writeFile(srcFile, html) (or ImportHandler calls fs.rename(srcFile, destFile) / soffice writes its converted output to the path), the open syscall follows the symlink and either reads from or overwrites the linked target. For deployments where the Etherpad process runs as a privileged user (notably some Docker base images that run as root, snap confinement edge cases, or hand-rolled systemd units), t…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-55086 has been found in ep_etherpad-lite.
Attackers can target a specific entry point like ExportHandler over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.2/10.
What to do: upgrade ep_etherpad-lite to 3.1.0 or later.
If unsure, ask your IT team or search "ep_etherpad-lite CVE-2026-55086" on the vendor's site.

CVE-2026-55086 (ep_etherpad-lite) — CWE-59 / CVSS v3 4.2
Attack vector: local / no user interaction
Attack surface: ExportHandler / ImportHandler / soffice / develop
Patched: 3.1.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-59) exists in ep_etherpad-lite. Attackers reach the vulnerable code path via ExportHandler.

📍 Affected scope

Check the vendor advisory for the affected versions of ep_etherpad-lite. Attack surface: ExportHandler / ImportHandler / soffice / develop.

🔥 Severity

Severity: Medium (CVSS 4.2/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.1.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'ep_etherpad-lite' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'ep_etherpad-lite' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で ep_etherpad-lite を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade ep_etherpad-lite to 3.1.0

    ステージング環境で 3.1.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

npm ep_etherpad-lite
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.1.0"}]}]

References

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