High SSRF exploit reference

CVE-2026-39383 — Gotenberg unauthenticated blind SSRF via unfiltered webhook URL

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.

Published May 5, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.3% (30-day exploitation probability)+3
Technical severity (high)+6
CISA SSVC: exploitation "poc"+5
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.31%

ahead of 22% of scored CVEs · Oct 15, 2026

Affects

Gotenberg

CVSS base

7.2

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented mitigation — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Gotenberg Gotenberg, Thecodingmachine Gotenberg).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the documented mitigations until a definitive fix is available.
Search available logs for exploit probes matching the vulnerability class (ssrf), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Gotenberg	Gotenberg	version < 8.31.0	Vulnerable	CVE Program (cve.org) e CISA ADP
Thecodingmachine	Gotenberg	≥ 8.29.1 and < 8.31.0	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.9	CVSS 4.0	Medium	—	—	security-advisories@github.com via NIST National Vulnerability Database
6.9	CVSS 4.0	Medium	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
7.2	CVSS 3.1	High	3.9	2.7	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-918 · Server-Side Request Forgery (SSRF)

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.31%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Monitor outbound requests from the server to internal IPs and cloud metadata endpoints.

web/proxy/WAF logsnetwork IDS/IPSegress traffic

Timeline

What happened to this CVE, newest first.

2026
Affected products added · gotenberg/gotenberg
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 7.2
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
May 5, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

github.com/gotenberg/gotenberg/security/advisories/GHSA-5vh4-rgv7-p9g4
Exploit, Mitigation, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database

Elsewhere on this site

Gotenberg
every CVE for this vendor

SSRF
same class

CWE-918
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-45742 Gotenberg: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') Aug 19, 2026
High CVE-2026-45741 Gotenberg: SSRF deny-list bypass in IsPublicIP via IPv6 6to4 / NAT64 / site-local prefixes Aug 19, 2026
High CVE-2026-44829 Gotenberg: Path traversal in zip entry name via Windows-style separators in upload filename Aug 19, 2026
High CVE-2026-55229 Gotenberg: SSRF via LibreOffice document processing Jul 10, 2026
Medium CVE-2026-42597 Gotenberg: Chromium URL conversion routes read arbitrary files under /tmp via file:// scheme May 14, 2026
High CVE-2026-42594 Gotenberg: Unauthenticated denial of service via echo.Context pool reuse in webhook async goroutine May 14, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-39383 is "Gotenberg unauthenticated blind SSRF via unfiltered webhook URL", rated High. It affects Gotenberg (Gotenberg); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.2 describes technical severity. EPSS 0.31% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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