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CVE-2026-55696 medium CVSS 4.3

Cross-Site Scripting (XSS) in privatebin/privatebin (CVE-2026-55696)

Summary

Cross-site scripting in privatebin/privatebin (CVE-2026-55696). Risk of unauthorized operations or information disclosure. Exploitable via lang. Mitigation: upgrade to 2.0.5 or later.

Original description

The description as published by the source.

Summary

Stored cross-site scripting (XSS) in PrivateBin's attachment download link. An anonymous attacker can create a paste with a text/html attachment that, with certain user interaction, bypasses protections similar to CVE-2022-24833. When a victim opens the "Download attachment" link in a new tab, the attacker's inline JavaScript executes in the PrivateBin instance's origin with full same-origin capability (cookie/localStorage access, same-origin fetch).

This is an incomplete fix of CVE-2022-24833. The original fix only applies to the inline preview blob (in case of SVG), never to the download link's blob. Thus a text/html (or image/svg) attachment completely bypasses sanitization, re-enabling the exact attack class on instances that don't enforce the recommended Content-Security-Policy, but with a slightly different attack process.

Instances using the default recommended CSP are protected (the blob inherits script-src 'self', blocking inline scripts). The vulnerability affects instances where CSP is weakened, stripped, or absent, which is exactly the defense-in-depth scenario the CVE-2022-24833 fix was meant to cover.

Requires fileupload = true (non-default) and a non-recommended CSP configuration.

Details

In js/privatebin.js, the function AttachmentViewer.setAttachment (line 2982) processes decrypted attachment data. Since PrivateBin uses zero-kn…

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-2026-55696 has been found in privatebin/privatebin.
Attackers can target a specific entry point like lang over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.3/10.
What to do: upgrade privatebin/privatebin to 2.0.5 or later.
If unsure, ask your IT team or search "privatebin/privatebin CVE-2026-55696" on the vendor's site.

CVE-2026-55696 (privatebin/privatebin) — CWE-79 / CVSS v3 4.3
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: lang / window.open
Patched: 2.0.5 — 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

Cross-site scripting (XSS) (CWE-79) exists in privatebin/privatebin. Attackers reach the vulnerable code path via lang without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of privatebin/privatebin. Attack surface: lang / window.open.

🔥 Severity

Severity: Medium (CVSS 4.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.0.5.

🛡️ 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 'privatebin/privatebin' . 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 'privatebin/privatebin' . | 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 privatebin/privatebin 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 privatebin/privatebin to 2.0.5

    ステージング環境で 2.0.5 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

composer privatebin/privatebin
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.5"}]}]
Packagist privatebin/privatebin
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.5"}]}]

References

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