SSRF (Server-Side Request Forgery) in github.com/gotenberg/gotenberg/v8 (CVE-2026-40280)
Summary
SSRF in github.com/gotenberg/gotenberg/v8 (CVE-2026-40280). Confidential information can be exposed externally. Exploitable via downloadFrom. Mitigation: upgrade to 8.31.0 or later.
Original description
The description as published by the source.
Gotenberg is an API-based document conversion tool. In versions 8.30.1 and earlier, the default private-IP deny-lists for the --webhook-deny-list and --api-download-from-deny-list flags use a case-sensitive regular expression (^https?://) to match URL schemes. Because Go's net/url.Parse() normalizes the scheme to lowercase before establishing the outbound TCP connection, an attacker can bypass the deny-list by simply capitalizing part of the URL scheme (e.g., HTTP://, HTTPS://, or Http://). This allows unauthenticated requests to reach internal network services, including private IP ranges, loopback addresses, and cloud instance metadata endpoints such as HTTP://169.254.169.254/latest/meta-data/.
This bypasses the same security control that was patched in CVE-2026-27018.
This issue has been fixed in version 8.31.0.
Source: NIST National Vulnerability Database 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-2026-40280 has been found in github.com/gotenberg/gotenberg/v8.
Attackers can target a specific entry point like downloadFrom over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: upgrade github.com/gotenberg/gotenberg/v8 to 8.31.0 or later.
If unsure, ask your IT team or search "github.com/gotenberg/gotenberg/v8 CVE-2026-40280" on the vendor's site.
CVE-2026-40280 (github.com/gotenberg/gotenberg/v8) — CWE-918 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: downloadFrom / FilterDeadline
Patched: 8.31.0 — 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.
SSRF (CWE-918) exists in github.com/gotenberg/gotenberg/v8. Attackers reach the vulnerable code path via downloadFrom without authentication.
Check the vendor advisory for the affected versions of github.com/gotenberg/gotenberg/v8. Attack surface: downloadFrom / FilterDeadline.
Severity: High (CVSS 7.5/10). Confidential information can be exposed externally.
Update to 8.31.0.
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 'github.com/gotenberg/gotenberg/v8' . 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
-
1Identify exposure identify
grep -r 'github.com/gotenberg/gotenberg/v8' . | 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
github.com/gotenberg/gotenberg/v8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 github.com/gotenberg/gotenberg/v8 to 8.31.0ステージング環境で 8.31.0 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。
-
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
- advisory github.com
- package github.com
- patch github.com
- web github.com
- web github.com