CVE-2026-62685: File Browser: Colliding username normalization… (CVSS 8.1)

CVE List Score used 8.1

File Browser: Colliding username normalization gives two users the same home directory

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.17, File Browser builds new user scopes from usernames passed through cleanUsername() when Signup=true and CreateUserDir=true, but the many-to-one normalization can collapse usernames such as team/one, team one, and team-one to the same home directory without checking whether the resulting scope is already taken, allowing a second registrant to gain full read and write access to another user's files. This issue is fixed in version 2.63.17.

Record: CVE-2026-62685
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-647, CWE-706
Updated: 2026-11-02

EUVDEUVD-2026-44708 8.1

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.17, File Browser builds new user scopes from usernames passed through cleanUsername() when Signup=true and CreateUserDir=true, but the many-to-one normalization can collapse usernames such as team/one, team one, and team-one to the same home directory without checking whether the resulting scope is already taken, allowing a second registrant to gain full read and write access to another user's files. This issue is fixed in version 2.63.17.

Record: EUVD-2026-44708
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

GitHub AdvisoriesGHSA-7rc3-g7h6-22m7 8.1

File Browser: Colliding username normalization gives two users the same home directory

Summary

FileBrowser confines each user to a scope: a home directory that acts as the boundary for everything they can read or write. When self-registration and automatic home-directory creation are both enabled (Signup=true and CreateUserDir=true), a new user's scope is built from their username after it passes through cleanUsername(). That function rewrites the name: it strips .. and replaces every character outside 0-9A-Za-z@_\-. with -.

The problem is that this rewrite is many-to-one: different usernames can produce the same result, and FileBrowser never checks whether the resulting scope is already taken. So team/one, team one, and team-one all collapse to the same directory name, and whoever registers second is handed the same home directory as the first user instead of an isolated one.

This breaks per-user isolation. An attacker can pick a username that normalizes onto a victim's directory (for example registering alice/ or al..ice to land in alice's home) and gain full read and write access to that victim's files. Because username uniqueness is enforced on the raw name, both accounts coexist normally and neither user is warned that they share storage.

Details

1. The home directory is built straight from the cleaned username (settings/dir.go:30)

// MakeUserDir, when CreateUserDir is true:
username = cleanUsername(username)
// ...
userScope = path.Join(s.UserHomeBasePath, username)   // line 30
userScope = path.Join("/", userScope)                 // line 33

The user's scope is path.Join(UserHomeBasePath, cleanUsername(username)).

2. cleanUsername collapses distinct inputs to the same output (settings/dir.go:42-52)

func cleanUsername(s string) string {
    s = strings.Trim(s, " ")
    s = strings.ReplaceAll(s, "..", "")                       // line 45, deletes ".."
    s = invalidFilenameChars.ReplaceAllString(s, "-")         // line 48, any non [0-9A-Za-z@_.-] -> "-"
    s = dashes.ReplaceAllString(s, "-")                       // line 51, collapse repeated "-"
    return s
}

Because several characters all map to - (and .. is simply deleted), many different usernames produce the same output: team/one, team one, team:one, and team-one all become team-one, and a..b becomes ab. Usernames that are unique on their own end up pointing at one shared directory name.

3. No scope-uniqueness check exists

Username uniqueness is enforced on the raw username (Storm id), but nothing enforces uniqueness of the derived Scope. signupHandler writes the colliding scope back to the user (http/auth.go:198-203) and saves the account; the second registrant simply reuses the first registrant's home directory (MakeUserDir calls MkdirAll, which is idempotent).

PoC

Tested against filebrowser/filebrowser:v2.63.15 with Signup=true and CreateUserDir=true (default minimumPasswordLength is 12).

Attack Vector: register a colliding username and read/overwrite another user's files:

#1. Create a dir in /tmp and start a fresh v2.63.15 container
mkdir -p /tmp/filebrowser-test/srv
docker run -d --name filebrowser-test -p 8090:80 -v /tmp/filebrowser-test/srv:/srv filebrowser/filebrowser:v2.63.15 && sleep 4
B=http://localhost:8090; PW='CollidePw12345!'

#2. Admin logs in and enables the two required non-default settings: signup=true and createUserDir=true
AP=$(docker logs filebrowser-test 2>&1 | grep -o 'password: .*' | awk '{print $2}')
AT=$(curl -s -X POST $B/api/login -H 'Content-Type: application/json' -d "{\"username\":\"admin\",\"password\":\"$AP\"}")
curl -s -H "X-Auth: $AT" $B/api/settings \
  | python3 -c "import sys,json;d=json.load(sys.stdin);d['signup']=True;d['createUserDir']=True;print(json.dumps(d))" \
  | curl -s -X PUT $B/api/settings -H "X-Auth: $AT" -H 'Content-Type: application/json' -d @-

#3. Register the victim teamone-x
curl -s -X POST $B/api/signup -H 'Content-Type: application/json'…

Record: GHSA-7rc3-g7h6-22m7
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-647, CWE-706
Updated: 2026-11-02

NVD 8.1

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.17, File Browser builds new user scopes from usernames passed through cleanUsername() when Signup=true and CreateUserDir=true, but the many-to-one normalization can collapse usernames such as team/one, team one, and team-one to the same home directory without checking whether the resulting scope is already taken, allowing a second registrant to gain full read and write access to another user's files. This issue is fixed in version 2.63.17.

Record: CVE-2026-62685
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-647, CWE-706
Updated: 2026-11-02

OSV 8.1

File Browser: Colliding username normalization gives two users the same home directory

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.17, File Browser builds new user scopes from usernames passed through cleanUsername() when Signup=true and CreateUserDir=true, but the many-to-one normalization can collapse usernames such as team/one, team one, and team-one to the same home directory without checking whether the resulting scope is already taken, allowing a second registrant to gain full read and write access to another user's files. This issue is fixed in version 2.63.17.

Record: CVE-2026-62685
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-647, CWE-706
Updated: 2026-11-02

OSVGHSA-7rc3-g7h6-22m7 8.1

File Browser: Colliding username normalization gives two users the same home directory

Summary

FileBrowser confines each user to a scope: a home directory that acts as the boundary for everything they can read or write. When self-registration and automatic home-directory creation are both enabled (Signup=true and CreateUserDir=true), a new user's scope is built from their username after it passes through cleanUsername(). That function rewrites the name: it strips .. and replaces every character outside 0-9A-Za-z@_\-. with -.

The problem is that this rewrite is many-to-one: different usernames can produce the same result, and FileBrowser never checks whether the resulting scope is already taken. So team/one, team one, and team-one all collapse to the same directory name, and whoever registers second is handed the same home directory as the first user instead of an isolated one.

This breaks per-user isolation. An attacker can pick a username that normalizes onto a victim's directory (for example registering alice/ or al..ice to land in alice's home) and gain full read and write access to that victim's files. Because username uniqueness is enforced on the raw name, both accounts coexist normally and neither user is warned that they share storage.

Details

1. The home directory is built straight from the cleaned username (settings/dir.go:30)

// MakeUserDir, when CreateUserDir is true:
username = cleanUsername(username)
// ...
userScope = path.Join(s.UserHomeBasePath, username)   // line 30
userScope = path.Join("/", userScope)                 // line 33

The user's scope is path.Join(UserHomeBasePath, cleanUsername(username)).

2. cleanUsername collapses distinct inputs to the same output (settings/dir.go:42-52)

func cleanUsername(s string) string {
    s = strings.Trim(s, " ")
    s = strings.ReplaceAll(s, "..", "")                       // line 45, deletes ".."
    s = invalidFilenameChars.ReplaceAllString(s, "-")         // line 48, any non [0-9A-Za-z@_.-] -> "-"
    s = dashes.ReplaceAllString(s, "-")                       // line 51, collapse repeated "-"
    return s
}

Because several characters all map to - (and .. is simply deleted), many different usernames produce the same output: team/one, team one, team:one, and team-one all become team-one, and a..b becomes ab. Usernames that are unique on their own end up pointing at one shared directory name.

3. No scope-uniqueness check exists

Username uniqueness is enforced on the raw username (Storm id), but nothing enforces uniqueness of the derived Scope. signupHandler writes the colliding scope back to the user (http/auth.go:198-203) and saves the account; the second registrant simply reuses the first registrant's home directory (MakeUserDir calls MkdirAll, which is idempotent).

PoC

Tested against filebrowser/filebrowser:v2.63.15 with Signup=true and CreateUserDir=true (default minimumPasswordLength is 12).

Attack Vector: register a colliding username and read/overwrite another user's files:

#1. Create a dir in /tmp and start a fresh v2.63.15 container
mkdir -p /tmp/filebrowser-test/srv
docker run -d --name filebrowser-test -p 8090:80 -v /tmp/filebrowser-test/srv:/srv filebrowser/filebrowser:v2.63.15 && sleep 4
B=http://localhost:8090; PW='CollidePw12345!'

#2. Admin logs in and enables the two required non-default settings: signup=true and createUserDir=true
AP=$(docker logs filebrowser-test 2>&1 | grep -o 'password: .*' | awk '{print $2}')
AT=$(curl -s -X POST $B/api/login -H 'Content-Type: application/json' -d "{\"username\":\"admin\",\"password\":\"$AP\"}")
curl -s -H "X-Auth: $AT" $B/api/settings \
  | python3 -c "import sys,json;d=json.load(sys.stdin);d['signup']=True;d['createUserDir']=True;print(json.dumps(d))" \
  | curl -s -X PUT $B/api/settings -H "X-Auth: $AT" -H 'Content-Type: application/json' -d @-

#3. Register the victim teamone-x
curl -s -X POST $B/api/signup -H 'Content-Type: application/json'…

Record: GHSA-7rc3-g7h6-22m7
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-647, CWE-706
Updated: 2026-11-02

OSVGO-2026-6024 No score

File Browser: Colliding username normalization gives two users the same home directory in github.com/filebrowser/filebrowser

File Browser: Colliding username normalization gives two users the same home directory in github.com/filebrowser/filebrowser

Record: GO-2026-6024
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	through 2.63.16	2.63.17
`github.com/filebrowser/filebrowser/v2` Go	before 2.63.17	2.63.17
`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

CVE-2026-62685

Attack profile

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