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CVE-2026-42595

Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-List Bypass

8.6 HighFix available

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) has no default protection against HTTP/HTTPS-based SSRF. The default deny-list regex only blocks file:// URIs. An unauthenticated attacker can point Chromium at any internal IP — including loopback, RFC 1918 ranges, and cloud metadata endpoints — and receive the response rendered as a PDF. Additionally, even when operators configure a custom deny-list, the protection is bypassed via HTTP redirects. Gotenberg's Chromium instance follows 302 redirects from an attacker-controlled external URL to internal targets without re-validating the redirect destination against the deny-list. This vulnerability is fixed in 8.32.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.31%Up 0.3 points since May 15, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.6

Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-List Bypass

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) has no default protection against HTTP/HTTPS-based SSRF. The default deny-list regex only blocks file:// URIs. An unauthenticated attacker can point Chromium at any internal IP — including loopback, RFC 1918 ranges, and cloud metadata endpoints — and receive the response rendered as a PDF. Additionally, even when operators configure a custom deny-list, the protection is bypassed via HTTP redirects. Gotenberg's Chromium instance follows 302 redirects from an attacker-controlled external URL to internal targets without re-validating the redirect destination against the deny-list. This vulnerability is fixed in 8.32.0.

Record
CVE-2026-42595
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-918
Updated
2026-11-02
EUVDEUVD-2026-30318 8.6

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) has no default protection against HTTP/HTTPS-based SSRF. The default deny-list regex only blocks file:// URIs. An unauthenticated attacker can point Chromium at any internal IP — including loopback, RFC 1918 ranges, and cloud metadata endpoints — and receive the response rendered as a PDF. Additionally, even when operators configure a custom deny-list, the protection is bypassed via HTTP redirects. Gotenberg's Chromium instance follows 302 redirects from an attacker-controlled external URL to internal targets without re-validating the redirect destination against the deny-list. This vulnerability is fixed in 8.32.0.

Record
EUVD-2026-30318
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-chwh-f6gm-r836 8.6

Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-List Bypass

A review of 4 published Gotenberg security advisories exposed an SSRF issue. GHSA-pjrr-jgp4-v2fm covers SSRF via the downloadFrom endpoint. GHSA-pcrp-7g9h-7qhp covers SSRF via the webhook endpoint. Neither advisory addresses SSRF through the primary Chromium URL-to-PDF conversion endpoint (/forms/chromium/convert/url), which has no default deny-list for HTTP/HTTPS targets. The redirect-based deny-list bypass described here also applies to downloadFrom and webhook but is a separate finding from the initial request validation those advisories cover.

Summary

Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) has no default protection against HTTP/HTTPS-based SSRF. The default deny-list regex only blocks file:// URIs. An unauthenticated attacker can point Chromium at any internal IP — including loopback, RFC 1918 ranges, and cloud metadata endpoints — and receive the response rendered as a PDF.

Additionally, even when operators configure a custom deny-list, the protection is bypassed via HTTP redirects. Gotenberg's Chromium instance follows 302 redirects from an attacker-controlled external URL to internal targets without re-validating the redirect destination against the deny-list.

What makes this particularly notable is that Gotenberg's secondary features — downloadFrom and webhook — ship with default deny-lists that explicitly block RFC 1918 and link-local addresses. The primary feature, the one that literally takes a URL and fetches it server-side, does not.

Details

Finding 1: Zero default SSRF protection on Chromium URL endpoint

The Chromium URL endpoint is the core feature of Gotenberg. It accepts a URL, tells headless Chromium to fetch it, and returns the rendered page as a PDF. The default deny-list is configured in pkg/modules/chromium/chromium.go and the value shipped in Docker is:

^file:(?!//\/tmp/).*

This regex only blocks file:// URIs outside of /tmp/. HTTP and HTTPS requests to any host — including 127.0.0.1, 10.x.x.x, 192.168.x.x, and 169.254.169.254 — are not filtered at all.

Meanwhile, the downloadFrom and webhook endpoints use deny-lists that explicitly block loopback, RFC 1918, and cloud metadata IPs. The developer clearly understood the SSRF risk but the protection was not applied to the main Chromium conversion endpoint.

Finding 2: Redirect-based SSRF bypass on all endpoints

Both downloadFrom and webhook use Go's default http.Client{} with no CheckRedirect function. Go follows up to 10 redirects automatically. The deny-list is a pre-flight check on the initial URL only. Once the request is in flight, redirects are followed transparently and the application never re-validates the destination.

The Chromium browser similarly follows redirects without restriction. Even if an operator configures a custom deny-list on the Chromium URL endpoint, an attacker hosts a redirect server that passes initial validation and then redirects Chromium to an internal target.

PoC

Tested on Docker using gotenberg/gotenberg:8 (v8.30.1) on localhost:3000. No authentication is required on any endpoint.

Environment:

$ curl http://localhost:3000/version
8.30.1

$ curl http://localhost:3000/health
{"status":"up","details":{"chromium":{"status":"up"},"libreoffice":{"status":"up"}}}

1. Control — external URL works as expected:

$ curl -X POST http://localhost:3000/forms/chromium/convert/url \
    --form 'url=http://example.com' \
    -o test.pdf -w "HTTP %{http_code}, Size: %{size_download} bytes"

HTTP 200, Size: 14961 bytes
$ file test.pdf
test.pdf: PDF document, version 1.4, 1 page(s)

2. Control — file:// protocol is correctly blocked by default deny-list:

$ curl -X POST http://localhost:3000/forms/chromium/convert/url \
    --form 'url=file:///etc/passwd' \
    -w "HTTP %{http_code}"

HTTP 403
Body: Forbidden

3. SSRF to localhost — NOT blocked:

$ curl -X POST…
Record
GHSA-chwh-f6gm-r836
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-918
Updated
2026-11-02
NVD 8.6

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) has no default protection against HTTP/HTTPS-based SSRF. The default deny-list regex only blocks file:// URIs. An unauthenticated attacker can point Chromium at any internal IP — including loopback, RFC 1918 ranges, and cloud metadata endpoints — and receive the response rendered as a PDF. Additionally, even when operators configure a custom deny-list, the protection is bypassed via HTTP redirects. Gotenberg's Chromium instance follows 302 redirects from an attacker-controlled external URL to internal targets without re-validating the redirect destination against the deny-list. This vulnerability is fixed in 8.32.0.

Record
CVE-2026-42595
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-918
Updated
2026-11-02
OSV 8.6

Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-List Bypass

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) has no default protection against HTTP/HTTPS-based SSRF. The default deny-list regex only blocks file:// URIs. An unauthenticated attacker can point Chromium at any internal IP — including loopback, RFC 1918 ranges, and cloud metadata endpoints — and receive the response rendered as a PDF. Additionally, even when operators configure a custom deny-list, the protection is bypassed via HTTP redirects. Gotenberg's Chromium instance follows 302 redirects from an attacker-controlled external URL to internal targets without re-validating the redirect destination against the deny-list. This vulnerability is fixed in 8.32.0.

Record
CVE-2026-42595
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-918
Updated
2026-11-02
OSVGHSA-chwh-f6gm-r836 8.6

Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-List Bypass

A review of 4 published Gotenberg security advisories exposed an SSRF issue. GHSA-pjrr-jgp4-v2fm covers SSRF via the downloadFrom endpoint. GHSA-pcrp-7g9h-7qhp covers SSRF via the webhook endpoint. Neither advisory addresses SSRF through the primary Chromium URL-to-PDF conversion endpoint (/forms/chromium/convert/url), which has no default deny-list for HTTP/HTTPS targets. The redirect-based deny-list bypass described here also applies to downloadFrom and webhook but is a separate finding from the initial request validation those advisories cover.

Summary

Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) has no default protection against HTTP/HTTPS-based SSRF. The default deny-list regex only blocks file:// URIs. An unauthenticated attacker can point Chromium at any internal IP — including loopback, RFC 1918 ranges, and cloud metadata endpoints — and receive the response rendered as a PDF.

Additionally, even when operators configure a custom deny-list, the protection is bypassed via HTTP redirects. Gotenberg's Chromium instance follows 302 redirects from an attacker-controlled external URL to internal targets without re-validating the redirect destination against the deny-list.

What makes this particularly notable is that Gotenberg's secondary features — downloadFrom and webhook — ship with default deny-lists that explicitly block RFC 1918 and link-local addresses. The primary feature, the one that literally takes a URL and fetches it server-side, does not.

Details

Finding 1: Zero default SSRF protection on Chromium URL endpoint

The Chromium URL endpoint is the core feature of Gotenberg. It accepts a URL, tells headless Chromium to fetch it, and returns the rendered page as a PDF. The default deny-list is configured in pkg/modules/chromium/chromium.go and the value shipped in Docker is:

^file:(?!//\/tmp/).*

This regex only blocks file:// URIs outside of /tmp/. HTTP and HTTPS requests to any host — including 127.0.0.1, 10.x.x.x, 192.168.x.x, and 169.254.169.254 — are not filtered at all.

Meanwhile, the downloadFrom and webhook endpoints use deny-lists that explicitly block loopback, RFC 1918, and cloud metadata IPs. The developer clearly understood the SSRF risk but the protection was not applied to the main Chromium conversion endpoint.

Finding 2: Redirect-based SSRF bypass on all endpoints

Both downloadFrom and webhook use Go's default http.Client{} with no CheckRedirect function. Go follows up to 10 redirects automatically. The deny-list is a pre-flight check on the initial URL only. Once the request is in flight, redirects are followed transparently and the application never re-validates the destination.

The Chromium browser similarly follows redirects without restriction. Even if an operator configures a custom deny-list on the Chromium URL endpoint, an attacker hosts a redirect server that passes initial validation and then redirects Chromium to an internal target.

PoC

Tested on Docker using gotenberg/gotenberg:8 (v8.30.1) on localhost:3000. No authentication is required on any endpoint.

Environment:

$ curl http://localhost:3000/version
8.30.1

$ curl http://localhost:3000/health
{"status":"up","details":{"chromium":{"status":"up"},"libreoffice":{"status":"up"}}}

1. Control — external URL works as expected:

$ curl -X POST http://localhost:3000/forms/chromium/convert/url \
    --form 'url=http://example.com' \
    -o test.pdf -w "HTTP %{http_code}, Size: %{size_download} bytes"

HTTP 200, Size: 14961 bytes
$ file test.pdf
test.pdf: PDF document, version 1.4, 1 page(s)

2. Control — file:// protocol is correctly blocked by default deny-list:

$ curl -X POST http://localhost:3000/forms/chromium/convert/url \
    --form 'url=file:///etc/passwd' \
    -w "HTTP %{http_code}"

HTTP 403
Body: Forbidden

3. SSRF to localhost — NOT blocked:

$ curl -X POST…
Record
GHSA-chwh-f6gm-r836
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-918
Updated
2026-11-02
OSVGO-2026-5324 No score

Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-List Bypass in github.com/gotenberg/gotenberg

Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-List Bypass in github.com/gotenberg/gotenberg

Record
GO-2026-5324
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/gotenberg/gotenberg/v8
Go
 before 8.32.0
8.32.0
github.com/gotenberg/gotenberg/v7
Go
 All versions None known
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-42595 is a high vulnerability (CVSS 8.6) in Gotenberg, published May 11, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 24th percentile. Fixed in github.com/gotenberg/gotenberg/v8 8.32.0.

References

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