Cross-Site Scripting (XSS) in yourls/yourls (CVE-2026-63135)
Summary
Cross-site scripting in yourls/yourls (CVE-2026-63135). Data can be tampered with by attackers. Exploitable via Referer header. Mitigation: upgrade to 1.10.4 or later.
Original description
The description as published by the source.
YOURLS is a self-hosted, customizable URL shortener written in PHP. From 1.5.1 until 1.10.4, YOURLS stores the HTTP Referer header through yourls_get_referrer(), yourls_sanitize_url_safe(), and yourls_log_redirect(), then aggregates the value in yourls-infos.php and passes the derived domain through yourls_get_domain(), yourls_stats_pie(), and yourls_google_array_to_data_table(). The chart builder concatenates labels into inline JavaScript without JavaScript-string escaping, so an unauthenticated attacker can poison the statistics of an existing short URL with a crafted referrer. When an administrator or public stats-page viewer opens the affected statistics page, attacker-controlled JavaScript executes in the YOURLS origin and can access admin-visible data, the API signature token, and privileged same-origin actions. This issue is fixed in version 1.10.4.
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-2026-63135 has been found in yourls/yourls.
Attackers can target a specific entry point like Referer header over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.2/10.
What to do: upgrade yourls/yourls to 1.10.4 or later.
If unsure, ask your IT team or search "yourls/yourls CVE-2026-63135" on the vendor's site.
CVE-2026-63135 (yourls/yourls) — CWE-79 / CVSS v3 8.2
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: Referer header / Referer / YOURLS_PRIVATE_INFOS / false
Patched: 1.10.4 — 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.
Cross-site scripting (XSS) (CWE-79) exists in yourls/yourls. Attackers reach the vulnerable code path via Referer header without authentication.
Check the vendor advisory for the affected versions of yourls/yourls. Attack surface: Referer header / Referer / YOURLS_PRIVATE_INFOS / false.
Severity: High (CVSS 8.2/10). Data can be tampered with by attackers.
Update to 1.10.4.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'yourls/yourls' . 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
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1Identify exposure identify
grep -r 'yourls/yourls' . | 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
yourls/yourlsを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade yourls/yourls to 1.10.4ステージング環境で 1.10.4 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。
-
3Post-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
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- patch github.com
- web github.com
- web github.com