CVE-2026-35585: File Browser has a Command Injection via Hook… (CVSS 7.5)

CVE List Score used 7.5

File Browser has a Command Injection via Hook Runner

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. From 2.0.0 until 2.33.8, the hook system in File Browser — which executes administrator-defined shell commands on file events such as upload, rename, and delete — is vulnerable to OS command injection. Variable substitution for values like $FILE and $USERNAME is performed via os.Expand without sanitization. An attacker with file write permission can craft a malicious filename containing shell metacharacters, causing the server to execute arbitrary OS commands when the hook fires. This results in Remote Code Execution (RCE). This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations.

Record: CVE-2026-35585
CVSS 4.0: 7.5 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-78, CWE-88
Updated: 2026-11-02

EUVDEUVD-2026-19775 7.5

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. From 2.0.0 until 2.33.8, the hook system in File Browser — which executes administrator-defined shell commands on file events such as upload, rename, and delete — is vulnerable to OS command injection. Variable substitution for values like $FILE and $USERNAME is performed via os.Expand without sanitization. An attacker with file write permission can craft a malicious filename containing shell metacharacters, causing the server to execute arbitrary OS commands when the hook fires. This results in Remote Code Execution (RCE). This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations.

Record: EUVD-2026-19775
CVSS 4.0: 7.5 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-jvpw-637p-h3pw 7.5

File Browser has a Command Injection via Hook Runner

[!NOTE] This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations. To exploit this vulnerability, the instance administrator must turn on a feature and ignore all the warnings about known vulnerabilities. We're publishing this new advisory to make it clear that all vulnerabilities concerning this feature are disclosed.

For more information about tracking vulnerability issues related to the Command Execution features, check https://github.com/filebrowser/filebrowser/issues/5199.

Overview

The hook system in File Browser — which executes administrator-defined shell commands on file events such as upload, rename, and delete — is vulnerable to OS command injection. Variable substitution for values like $FILE and $USERNAME is performed via os.Expand without sanitization. An attacker with file write permission can craft a malicious filename containing shell metacharacters, causing the server to execute arbitrary OS commands when the hook fires. This results in Remote Code Execution (RCE).

Affected Location

File: runner/runner.go
Function: Runner.exec

Technical Details

Runner.exec expands template variables inside hook command strings using os.Expand:

// runner/runner.go
envMapping := func(key string) string {
    switch key {
    case "FILE":
        return path       // attacker-controlled filename
    case "USERNAME":
        return username   // attacker-controlled username
    // ...
    }
}

for i, arg := range command {
    if i == 0 { continue }
    command[i] = os.Expand(arg, envMapping) // expands $FILE, $USERNAME, etc.
}

The expanded value is then passed as a shell argument string. os.Expand performs plain string substitution with no escaping. If an admin has configured a hook such as:

sh -c "echo created $FILE"

...and an attacker creates a file named ; id #, the variable expansion produces:

sh -c "echo created /path/to/; id #"

The ; terminates the echo command and the shell executes id with server privileges. The # character comments out the remainder, preventing syntax errors.

This pattern is exploitable across all hook events: before_upload, after_upload, before_rename, after_rename, before_delete, after_delete, etc.

Attack Scenario / Reproduction Steps

Admin configures an after_upload hook: sh -c "echo created $FILE".
The attacker (authenticated user with upload permission) uploads a file named ; id #.
The upload succeeds and the hook fires automatically.
The server executes:
```
sh -c "echo created /uploads/; id #"
```
The id command runs, confirming RCE.

Impact

Any authenticated user with file create, upload, or rename permissions can achieve arbitrary RCE on the server when shell-based hooks are configured. The attacker does not need to know the exact hook command — any hook that embeds $FILE in a shell string is exploitable by crafting the filename accordingly.

Proof of Concept

package runner

import (
        "os"
        "testing"

        "github.com/filebrowser/filebrowser/v2/settings"
)

func TestPoC_FileHookInjection(t *testing.T) {
        // Simulate an admin-configured shell-based hook
        r := &Runner{
                Enabled: true,
                Settings: &settings.Settings{
                        Shell: []string{"sh", "-c"},
                        Commands: map[string][]string{
                                "after_upload": {"echo Uploaded $FILE"},
                        },
                },
        }

        // Malicious filename crafted by the attacker
        maliciousFilename := "/tmp/safe; id #"

        // Simulate the exec logic in runner/runner.go
        raw := r.Commands["after_upload"][0]
        command, _, _ := ParseCommand(r.Settings, raw)

        envMapping := func(key string) string {
                if key == "FILE" {
                  …

Record: GHSA-jvpw-637p-h3pw
CVSS 4.0: 7.5 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 7.2 HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-78, CWE-88
Updated: 2026-11-02

NVD 7.5

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. From 2.0.0 until 2.33.8, the hook system in File Browser — which executes administrator-defined shell commands on file events such as upload, rename, and delete — is vulnerable to OS command injection. Variable substitution for values like $FILE and $USERNAME is performed via os.Expand without sanitization. An attacker with file write permission can craft a malicious filename containing shell metacharacters, causing the server to execute arbitrary OS commands when the hook fires. This results in Remote Code Execution (RCE). This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations.

Record: CVE-2026-35585
CVSS 4.0: 7.5 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 7.2 HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-78, CWE-88
Updated: 2026-11-02

OSV 7.5

File Browser has a Command Injection via Hook Runner

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. From 2.0.0 until 2.33.8, the hook system in File Browser — which executes administrator-defined shell commands on file events such as upload, rename, and delete — is vulnerable to OS command injection. Variable substitution for values like $FILE and $USERNAME is performed via os.Expand without sanitization. An attacker with file write permission can craft a malicious filename containing shell metacharacters, causing the server to execute arbitrary OS commands when the hook fires. This results in Remote Code Execution (RCE). This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations.

Record: CVE-2026-35585
CVSS 4.0: 7.5 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-78, CWE-88
Updated: 2026-11-02

OSVGHSA-jvpw-637p-h3pw 7.5

File Browser has a Command Injection via Hook Runner

[!NOTE] This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations. To exploit this vulnerability, the instance administrator must turn on a feature and ignore all the warnings about known vulnerabilities. We're publishing this new advisory to make it clear that all vulnerabilities concerning this feature are disclosed.

For more information about tracking vulnerability issues related to the Command Execution features, check https://github.com/filebrowser/filebrowser/issues/5199.

Overview

The hook system in File Browser — which executes administrator-defined shell commands on file events such as upload, rename, and delete — is vulnerable to OS command injection. Variable substitution for values like $FILE and $USERNAME is performed via os.Expand without sanitization. An attacker with file write permission can craft a malicious filename containing shell metacharacters, causing the server to execute arbitrary OS commands when the hook fires. This results in Remote Code Execution (RCE).

Affected Location

File: runner/runner.go
Function: Runner.exec

Technical Details

Runner.exec expands template variables inside hook command strings using os.Expand:

// runner/runner.go
envMapping := func(key string) string {
    switch key {
    case "FILE":
        return path       // attacker-controlled filename
    case "USERNAME":
        return username   // attacker-controlled username
    // ...
    }
}

for i, arg := range command {
    if i == 0 { continue }
    command[i] = os.Expand(arg, envMapping) // expands $FILE, $USERNAME, etc.
}

The expanded value is then passed as a shell argument string. os.Expand performs plain string substitution with no escaping. If an admin has configured a hook such as:

sh -c "echo created $FILE"

...and an attacker creates a file named ; id #, the variable expansion produces:

sh -c "echo created /path/to/; id #"

The ; terminates the echo command and the shell executes id with server privileges. The # character comments out the remainder, preventing syntax errors.

This pattern is exploitable across all hook events: before_upload, after_upload, before_rename, after_rename, before_delete, after_delete, etc.

Attack Scenario / Reproduction Steps

Admin configures an after_upload hook: sh -c "echo created $FILE".
The attacker (authenticated user with upload permission) uploads a file named ; id #.
The upload succeeds and the hook fires automatically.
The server executes:
```
sh -c "echo created /uploads/; id #"
```
The id command runs, confirming RCE.

Impact

Any authenticated user with file create, upload, or rename permissions can achieve arbitrary RCE on the server when shell-based hooks are configured. The attacker does not need to know the exact hook command — any hook that embeds $FILE in a shell string is exploitable by crafting the filename accordingly.

Proof of Concept

package runner

import (
        "os"
        "testing"

        "github.com/filebrowser/filebrowser/v2/settings"
)

func TestPoC_FileHookInjection(t *testing.T) {
        // Simulate an admin-configured shell-based hook
        r := &Runner{
                Enabled: true,
                Settings: &settings.Settings{
                        Shell: []string{"sh", "-c"},
                        Commands: map[string][]string{
                                "after_upload": {"echo Uploaded $FILE"},
                        },
                },
        }

        // Malicious filename crafted by the attacker
        maliciousFilename := "/tmp/safe; id #"

        // Simulate the exec logic in runner/runner.go
        raw := r.Commands["after_upload"][0]
        command, _, _ := ParseCommand(r.Settings, raw)

        envMapping := func(key string) string {
                if key == "FILE" {
                  …

Record: GHSA-jvpw-637p-h3pw
CVSS 4.0: 7.5 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 7.2 HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-78, CWE-88
Updated: 2026-11-02

OSVGO-2026-5481 No score

File Browser has a Command Injection via Hook Runner in github.com/filebrowser/filebrowser

File Browser has a Command Injection via Hook Runner in github.com/filebrowser/filebrowser

Record: GO-2026-5481
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

Package	Affected	Fixed
`github.com/filebrowser/filebrowser/v2` Go	before 2.33.8	2.33.8
`github.com/filebrowser/filebrowser` 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

Recorded	Changed	Sources
Nov 6, 2026	affected, facts
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV, PoC in GitHub

CVE-2026-35585

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