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CVE-2026-48777

FileBrowser Quantum: Path Traversal in public share PATCH allows file ops outside shared directory

9.3 CriticalFix available

FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated. A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root. This issue has been fixed in versions 1.3.3-stable and 1.4.2-beta.

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
High
Availability
None

Exploit likelihood

0.55%Up 0.5 points since Jun 12, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.3

FileBrowser Quantum: Path Traversal in public share PATCH allows file ops outside shared directory

FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated. A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root. This issue has been fixed in versions 1.3.3-stable and 1.4.2-beta.

Record
CVE-2026-48777
CVSS 4.0
9.3 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-22
Updated
2026-11-02
EUVDEUVD-2026-37207 9.3

FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated. A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root. This issue has been fixed in versions 1.3.3-stable and 1.4.2-beta.

Record
EUVD-2026-37207
CVSS 4.0
9.3 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-qqqm-5547-774x 9.3

FileBrowser Quantum: Path traversal in public share PATCH allows file ops outside shared directory

Summary

publicPatchHandler in backend/http/public.go joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated.

A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root.

Verified on commit 869b640 (HEAD of main as of 2026-05-07).

Details

In backend/http/public.go the public PATCH handler accepts a JSON body with items[].fromPath and items[].toPath from the client, then prepends the share path before delegating to resourcePatchHandler:

// backend/http/public.go (publicPatchHandler)
for i := range req.Items {
    req.Items[i].FromSource = sourceName
    req.Items[i].FromPath   = utils.JoinPathAsUnix(d.share.Path, req.Items[i].FromPath) // line 372
    req.Items[i].ToSource   = sourceName
    req.Items[i].ToPath     = utils.JoinPathAsUnix(d.share.Path, req.Items[i].ToPath)   // line 374
}
d.Data = req
status, err := resourcePatchHandler(w, r, d)

utils.JoinPathAsUnix is a thin wrapper around filepath.Join, which calls filepath.Clean and resolves .. segments. By the time the joined path reaches resourcePatchHandler, every .. from the body has been collapsed:

// backend/http/resource.go (resourcePatchHandler)
cleanFromPath, err := utils.SanitizeUserPath(item.FromPath) // line 794
// ...
cleanToPath, err  := utils.SanitizeUserPath(item.ToPath)    // line 800

SanitizeUserPath (in backend/common/utils/file.go) checks for .. segments after filepath.Clean. Since the join already cleaned the path, no .. segment remains, the sanitizer returns success, and the move/copy/rename proceeds on the escaped target.

The share owner's user is substituted as the acting user for permission checks (d.user = shareCreatedByUser), so the access-control layer treats the request as if the share owner performed it. In a default configuration with no explicit access rules and DenyByDefault=false, Access.Permitted returns true for any path within the source, and the only remaining boundary is the source root itself (idx.Path in Index.GetRealPath).

The fix that landed for CVE-2026-44542 / GHSA-fwj3-42wh-8673 moved the sanitizer before the join in resourceBulkDeleteHandler (backend/http/resource.go:274) and in withHashFileHelper (backend/http/middleware.go:57). The PATCH variant in public.go follows the opposite order (join first, sanitize later) and was not updated.

For comparison, the same file's publicPutHandler uses the safe order:

// backend/http/public.go (publicPutHandler) -- safe order
cleanPath, err := utils.SanitizeUserPath(path)         // sanitize FIRST
if err != nil { return http.StatusBadRequest, err }
resolvedPath := utils.JoinPathAsUnix(d.share.Path, cleanPath) // then join

PoC

The bug reproduces deterministically with the project's own helpers, without needing the full server. The Go program below uses verbatim copies of SanitizeUserPath (from backend/common/utils/file.go) and JoinPathAsUnix (from backend/common/utils/main.go) and replays the exact sequence executed for one item in publicPatchHandler followed by resourcePatchHandler.

package main

import (
    "fmt"
    "path/filepath"
    "runtime"
    "strings"
)

// Verbatim from backend/common/utils/file.go
func SanitizeUserPath(userPath string) (string, error) {
    clean := filepath.Clean(userPath)
    for _, segment := range strings.Split(clean, string(filepath.Separator)) {
        if segment ==…
Record
GHSA-qqqm-5547-774x
CVSS 4.0
9.3 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-22
Updated
2026-11-02
NVD 9.3

FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated. A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root. This issue has been fixed in versions 1.3.3-stable and 1.4.2-beta.

Record
CVE-2026-48777
CVSS 4.0
9.3 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/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
Weakness
CWE-22
Updated
2026-11-02
OSV 9.3

FileBrowser Quantum: Path Traversal in public share PATCH allows file ops outside shared directory

FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated. A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root. This issue has been fixed in versions 1.3.3-stable and 1.4.2-beta.

Record
CVE-2026-48777
CVSS 4.0
9.3 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-22
Updated
2026-11-02
OSVGHSA-qqqm-5547-774x 9.3

FileBrowser Quantum: Path traversal in public share PATCH allows file ops outside shared directory

Summary

publicPatchHandler in backend/http/public.go joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated.

A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root.

Verified on commit 869b640 (HEAD of main as of 2026-05-07).

Details

In backend/http/public.go the public PATCH handler accepts a JSON body with items[].fromPath and items[].toPath from the client, then prepends the share path before delegating to resourcePatchHandler:

// backend/http/public.go (publicPatchHandler)
for i := range req.Items {
    req.Items[i].FromSource = sourceName
    req.Items[i].FromPath   = utils.JoinPathAsUnix(d.share.Path, req.Items[i].FromPath) // line 372
    req.Items[i].ToSource   = sourceName
    req.Items[i].ToPath     = utils.JoinPathAsUnix(d.share.Path, req.Items[i].ToPath)   // line 374
}
d.Data = req
status, err := resourcePatchHandler(w, r, d)

utils.JoinPathAsUnix is a thin wrapper around filepath.Join, which calls filepath.Clean and resolves .. segments. By the time the joined path reaches resourcePatchHandler, every .. from the body has been collapsed:

// backend/http/resource.go (resourcePatchHandler)
cleanFromPath, err := utils.SanitizeUserPath(item.FromPath) // line 794
// ...
cleanToPath, err  := utils.SanitizeUserPath(item.ToPath)    // line 800

SanitizeUserPath (in backend/common/utils/file.go) checks for .. segments after filepath.Clean. Since the join already cleaned the path, no .. segment remains, the sanitizer returns success, and the move/copy/rename proceeds on the escaped target.

The share owner's user is substituted as the acting user for permission checks (d.user = shareCreatedByUser), so the access-control layer treats the request as if the share owner performed it. In a default configuration with no explicit access rules and DenyByDefault=false, Access.Permitted returns true for any path within the source, and the only remaining boundary is the source root itself (idx.Path in Index.GetRealPath).

The fix that landed for CVE-2026-44542 / GHSA-fwj3-42wh-8673 moved the sanitizer before the join in resourceBulkDeleteHandler (backend/http/resource.go:274) and in withHashFileHelper (backend/http/middleware.go:57). The PATCH variant in public.go follows the opposite order (join first, sanitize later) and was not updated.

For comparison, the same file's publicPutHandler uses the safe order:

// backend/http/public.go (publicPutHandler) -- safe order
cleanPath, err := utils.SanitizeUserPath(path)         // sanitize FIRST
if err != nil { return http.StatusBadRequest, err }
resolvedPath := utils.JoinPathAsUnix(d.share.Path, cleanPath) // then join

PoC

The bug reproduces deterministically with the project's own helpers, without needing the full server. The Go program below uses verbatim copies of SanitizeUserPath (from backend/common/utils/file.go) and JoinPathAsUnix (from backend/common/utils/main.go) and replays the exact sequence executed for one item in publicPatchHandler followed by resourcePatchHandler.

package main

import (
    "fmt"
    "path/filepath"
    "runtime"
    "strings"
)

// Verbatim from backend/common/utils/file.go
func SanitizeUserPath(userPath string) (string, error) {
    clean := filepath.Clean(userPath)
    for _, segment := range strings.Split(clean, string(filepath.Separator)) {
        if segment ==…
Record
GHSA-qqqm-5547-774x
CVSS 4.0
9.3 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-22
Updated
2026-11-02
OSVGO-2026-5591 No score

FileBrowser Quantum: Path traversal in public share PATCH allows file ops outside shared directory in github.com/gtsteffaniak/filebrowser/backend

FileBrowser Quantum: Path traversal in public share PATCH allows file ops outside shared directory in github.com/gtsteffaniak/filebrowser/backend

Record
GO-2026-5591
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/gtsteffaniak/filebrowser/backend
Go
 before 0.0.0-20260518193514-28e9b81e438e
0.0.0-20260518193514-28e9b81e438e
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-2026-48777 is a critical vulnerability (CVSS 9.3) in Gtsteffaniak Filebrowser, published May 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.55%, the 46th percentile. Fixed in github.com/gtsteffaniak/filebrowser/backend 0.0.0-20260518193514-28e9b81e438e.

References

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