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CVE-2026-52832

Nuclio: Unauthenticated path traversal in spec.handler allows arbitrary file write in Dashboard container

4.9 MediumPublic exploitFix available

Nuclio is a "Serverless" framework for Real-Time Events and Data Processing. Prior to version 1.16.5, Nuclio Dashboard exposes POST /api/functions without authentication by default (NOP auth mode). The spec.handler field (e.g., mymodule:myfunction) is parsed by functionconfig.ParseHandler() which splits on : only — no path validation is applied to the module portion. This issue has been patched in version 1.16.5.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
High
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
None

Exploit likelihood

0.56%Up 0.1 points since Sep 3, 2026
90%50%10%1%

What each source reports

CVE List Score used 4.9

Nuclio: Unauthenticated path traversal in spec.handler allows arbitrary file write in Dashboard container

Nuclio is a "Serverless" framework for Real-Time Events and Data Processing. Prior to version 1.16.5, Nuclio Dashboard exposes POST /api/functions without authentication by default (NOP auth mode). The spec.handler field (e.g., mymodule:myfunction) is parsed by functionconfig.ParseHandler() which splits on : only — no path validation is applied to the module portion. This issue has been patched in version 1.16.5.

Record
CVE-2026-52832
CVSS 3.1
4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
EUVDEUVD-2026-70215 4.9

Nuclio is a "Serverless" framework for Real-Time Events and Data Processing. Prior to version 1.16.5, Nuclio Dashboard exposes POST /api/functions without authentication by default (NOP auth mode). The spec.handler field (e.g., mymodule:myfunction) is parsed by functionconfig.ParseHandler() which splits on : only — no path validation is applied to the module portion. This issue has been patched in version 1.16.5.

Record
EUVD-2026-70215
CVSS 3.1
4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-wpcj-rmv4-86qg 4.9

Nuclio: Unauthenticated path traversal in spec.handler allows arbitrary file write in Dashboard container

Summary

Nuclio Dashboard exposes POST /api/functions without authentication by default (NOP auth mode). The spec.handler field (e.g., mymodule:myfunction) is parsed by functionconfig.ParseHandler() which splits on : only — no path validation is applied to the module portion.

During function build, writeFunctionSourceCodeToTempFile() passes the module name directly to path.Join(tempDir, moduleFileName). Go's path.Join internally calls path.Clean, which resolves ../ sequences and allows the resolved path to escape tempDir. The function then calls os.WriteFile at the attacker-controlled path with attacker-controlled content (base64-decoded spec.build.functionSourceCode).

The write executes in the Dashboard container process running as uid=0 (root), allowing writes to any filesystem location the process can access: /tmp, /etc, /usr/local/bin, /etc/cron.d, and more.

  • CVSS 3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N — 7.5 (High)
  • CWE: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)
  • Affected versions: Nuclio <= 1.15.27 (latest at time of research, dynamically verified)

Details

Root Cause

The vulnerability spans three functions. The path from user input to disk write is:

1. ParseHandler — no path validation (pkg/functionconfig/handler.go:25-38):

// pkg/functionconfig/handler.go:25-38
func ParseHandler(handler string) (string, string, error) {
    moduleAndEntrypoint := strings.Split(handler, ":")
    switch len(moduleAndEntrypoint) {
    case 1:
        return "", moduleAndEntrypoint[0], nil
    case 2:
        // Returns moduleFileName verbatim — no path sanitization
        return moduleAndEntrypoint[0], moduleAndEntrypoint[1], nil
    default:
        return "", "", errors.Errorf("Invalid handler name %s", handler)
    }
}

Input "../../../../tmp/vul007_proof.txt:handler" returns moduleFileName = "../../../../tmp/vul007_proof.txt".

2. writeFunctionSourceCodeToTempFile — unsafe path construction (pkg/processor/build/builder.go:613-661):

// builder.go:624-657 (abridged)
tempDir, err := b.mkDirUnderTemp("source")
// tempDir = /tmp/nuclio-build-<random>/source

runtimeExtension, err := b.getRuntimeFileExtensionByName(b.options.FunctionConfig.Spec.Runtime)

moduleFileName, entrypoint, err := functionconfig.ParseHandler(b.options.FunctionConfig.Spec.Handler)
// moduleFileName = "../../../../tmp/vul007_proof.txt" — attacker-controlled

if !strings.Contains(moduleFileName, ".") {
    moduleFileName = fmt.Sprintf("%s.%s", moduleFileName, runtimeExtension)
}
// If moduleFileName already contains ".", no extension is appended
// "../../../../tmp/vul007_proof.txt" contains "." -> stays as-is

sourceFilePath := path.Join(tempDir, moduleFileName)
// path.Join("/tmp/nuclio-build-227825660/source", "../../../../tmp/vul007_proof.txt")
// = "/tmp/vul007_proof.txt"   <-- escaped tempDir

b.logger.DebugWith("Writing function source code to temporary file", "functionPath", sourceFilePath)
if err := os.WriteFile(sourceFilePath, decodedFunctionSourceCode, os.FileMode(0644)); err != nil {
    // Writes attacker-controlled bytes to attacker-controlled path

3. cleanupTempDir does not remove the traversal file (builder.go:1047-1061):

// builder.go:1053
err := os.RemoveAll(b.tempDir)
// Only removes /tmp/nuclio-build-<random>/ — traversal file outside this tree persists

Path Traversal Calculation

tempDir  = /tmp/nuclio-build-227825660/source   (depth from /: 3 components)
handler  = "../../../../tmp/vul007_proof.txt:handler"
module   = "../../../../tmp/vul007_proof.txt"

path.Join("/tmp/nuclio-build-227825660/source", "../../../../tmp/vul007_proof.txt")
= path.Clean("/tmp/nuclio-build-227825660/source/../../../../tmp/vul007_proof.txt")

Traversal:
  /tmp/nuclio-build-227825660/source  (start)
  ../  -> /tmp/nuclio-build-227825660
  ../  -> /tmp
  ../  -> / …
Record
GHSA-wpcj-rmv4-86qg
CVSS 3.1
4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
NVD 4.9

Nuclio is a "Serverless" framework for Real-Time Events and Data Processing. Prior to version 1.16.5, Nuclio Dashboard exposes POST /api/functions without authentication by default (NOP auth mode). The spec.handler field (e.g., mymodule:myfunction) is parsed by functionconfig.ParseHandler() which splits on : only — no path validation is applied to the module portion. This issue has been patched in version 1.16.5.

Record
CVE-2026-52832
CVSS 3.1
4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
OSV 4.9

Nuclio: Unauthenticated path traversal in spec.handler allows arbitrary file write in Dashboard container

Nuclio is a "Serverless" framework for Real-Time Events and Data Processing. Prior to version 1.16.5, Nuclio Dashboard exposes POST /api/functions without authentication by default (NOP auth mode). The spec.handler field (e.g., mymodule:myfunction) is parsed by functionconfig.ParseHandler() which splits on : only — no path validation is applied to the module portion. This issue has been patched in version 1.16.5.

Record
CVE-2026-52832
CVSS 3.1
4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
OSVGHSA-wpcj-rmv4-86qg 4.9

Nuclio: Unauthenticated path traversal in spec.handler allows arbitrary file write in Dashboard container

Summary

Nuclio Dashboard exposes POST /api/functions without authentication by default (NOP auth mode). The spec.handler field (e.g., mymodule:myfunction) is parsed by functionconfig.ParseHandler() which splits on : only — no path validation is applied to the module portion.

During function build, writeFunctionSourceCodeToTempFile() passes the module name directly to path.Join(tempDir, moduleFileName). Go's path.Join internally calls path.Clean, which resolves ../ sequences and allows the resolved path to escape tempDir. The function then calls os.WriteFile at the attacker-controlled path with attacker-controlled content (base64-decoded spec.build.functionSourceCode).

The write executes in the Dashboard container process running as uid=0 (root), allowing writes to any filesystem location the process can access: /tmp, /etc, /usr/local/bin, /etc/cron.d, and more.

  • CVSS 3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N — 7.5 (High)
  • CWE: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)
  • Affected versions: Nuclio <= 1.15.27 (latest at time of research, dynamically verified)

Details

Root Cause

The vulnerability spans three functions. The path from user input to disk write is:

1. ParseHandler — no path validation (pkg/functionconfig/handler.go:25-38):

// pkg/functionconfig/handler.go:25-38
func ParseHandler(handler string) (string, string, error) {
    moduleAndEntrypoint := strings.Split(handler, ":")
    switch len(moduleAndEntrypoint) {
    case 1:
        return "", moduleAndEntrypoint[0], nil
    case 2:
        // Returns moduleFileName verbatim — no path sanitization
        return moduleAndEntrypoint[0], moduleAndEntrypoint[1], nil
    default:
        return "", "", errors.Errorf("Invalid handler name %s", handler)
    }
}

Input "../../../../tmp/vul007_proof.txt:handler" returns moduleFileName = "../../../../tmp/vul007_proof.txt".

2. writeFunctionSourceCodeToTempFile — unsafe path construction (pkg/processor/build/builder.go:613-661):

// builder.go:624-657 (abridged)
tempDir, err := b.mkDirUnderTemp("source")
// tempDir = /tmp/nuclio-build-<random>/source

runtimeExtension, err := b.getRuntimeFileExtensionByName(b.options.FunctionConfig.Spec.Runtime)

moduleFileName, entrypoint, err := functionconfig.ParseHandler(b.options.FunctionConfig.Spec.Handler)
// moduleFileName = "../../../../tmp/vul007_proof.txt" — attacker-controlled

if !strings.Contains(moduleFileName, ".") {
    moduleFileName = fmt.Sprintf("%s.%s", moduleFileName, runtimeExtension)
}
// If moduleFileName already contains ".", no extension is appended
// "../../../../tmp/vul007_proof.txt" contains "." -> stays as-is

sourceFilePath := path.Join(tempDir, moduleFileName)
// path.Join("/tmp/nuclio-build-227825660/source", "../../../../tmp/vul007_proof.txt")
// = "/tmp/vul007_proof.txt"   <-- escaped tempDir

b.logger.DebugWith("Writing function source code to temporary file", "functionPath", sourceFilePath)
if err := os.WriteFile(sourceFilePath, decodedFunctionSourceCode, os.FileMode(0644)); err != nil {
    // Writes attacker-controlled bytes to attacker-controlled path

3. cleanupTempDir does not remove the traversal file (builder.go:1047-1061):

// builder.go:1053
err := os.RemoveAll(b.tempDir)
// Only removes /tmp/nuclio-build-<random>/ — traversal file outside this tree persists

Path Traversal Calculation

tempDir  = /tmp/nuclio-build-227825660/source   (depth from /: 3 components)
handler  = "../../../../tmp/vul007_proof.txt:handler"
module   = "../../../../tmp/vul007_proof.txt"

path.Join("/tmp/nuclio-build-227825660/source", "../../../../tmp/vul007_proof.txt")
= path.Clean("/tmp/nuclio-build-227825660/source/../../../../tmp/vul007_proof.txt")

Traversal:
  /tmp/nuclio-build-227825660/source  (start)
  ../  -> /tmp/nuclio-build-227825660
  ../  -> /tmp
  ../  -> / …
Record
GHSA-wpcj-rmv4-86qg
CVSS 3.1
4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
OSVGO-2026-6012 No score

Nuclio: Unauthenticated path traversal in spec.handler allows arbitrary file write in Dashboard container in github.com/nuclio/nuclio

Nuclio: Unauthenticated path traversal in spec.handler allows arbitrary file write in Dashboard container in github.com/nuclio/nuclio.

NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.

(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)

The additional affected modules and versions are: github.com/nuclio/nuclio before v1.16.5.

Record
GO-2026-6012
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/nuclio/nuclio
Go
 before 1.16.5
1.16.5
github.com/nuclio/nuclio
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

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
PoC in GitHubmdvpat/CVE-2026-52832-PoC-exploit-nuclio-dashboard2026-07-29

History

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

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

In short

CVE-2026-52832 is a medium vulnerability (CVSS 4.9) in Nuclio, published July 16, 2026. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 0.56%, the 46th percentile. Fixed in github.com/nuclio/nuclio 1.16.5.

References

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