SSRF (Server-Side Request Forgery) in github.com/gotenberg/gotenberg/v8 (CVE-2026-39383)
Summary
SSRF in github.com/gotenberg/gotenberg/v8 (CVE-2026-39383). Confidential information can be exposed externally. Exploitable via FilterDeadline. 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 version 8.29.1, an unauthenticated attacker with network access can force the server to make outbound HTTP POST requests to arbitrary internal or external destinations by supplying a crafted URL in the Gotenberg-Webhook-Url request header. The FilterDeadline function in filter.go is intended to gate outbound URLs, but when both the allow-list and deny-list are empty (the default configuration), it returns nil unconditionally and permits any URL.
This is a blind SSRF: Gotenberg POSTs the converted document to the webhook URL and only checks whether the response status code is an error, but never returns the target's response body to the attacker. An attacker can use this to probe internal network infrastructure by observing whether the error callback is invoked, force POST requests against internal services that perform side effects, and confirm reachability of cloud metadata endpoints. The retryable HTTP client issues up to 4 automatic retries per request, amplifying each probe.
This issue has been fixed in version 8.31.0. As a workaround, configure the GOTENBERG_API_WEBHOOK_ALLOW_LIST environment variable to restrict webhook URLs to known receivers, or set GOTENBERG_API_WEBHOOK_DENY_LIST to block RFC-1918 and link-local address ranges.
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-2026-39383 has been found in github.com/gotenberg/gotenberg/v8.
Attackers can target a specific entry point like FilterDeadline over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.2/10.
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-2026-39383" on the vendor's site.
CVE-2026-39383 (github.com/gotenberg/gotenberg/v8) — CWE-918 / CVSS v3 7.2
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: FilterDeadline / filter.go / nil / retryablehttp
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 FilterDeadline without authentication.
Check the vendor advisory for the affected versions of github.com/gotenberg/gotenberg/v8. Attack surface: FilterDeadline / filter.go / nil / retryablehttp.
Severity: High (CVSS 7.2/10). 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 nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com