VulnerabilityPublished 1 Jul 2026

CVE-2026-50138: goshs · WebDAV listener ignores --read-only, --upload-only, and --no-delete mode flags

Affects goshs.de/goshs/v2Source GCVE Database

Authoritative record:CVE-2026-50138· High 8.1

Not known to be exploited · CVSS 8.1 High : upgrade to 2.1.0 soon.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

8.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.1.0

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

Disclosed: evidence found.
CVE published 18 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CISA SSVC: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

CVE ID reserved
by GitHub, Inc.
3 Jun 202618:49 UTC, 76 days before disclosure
CVE published
on cve.org
18 Aug 202614:59 UTC, t = 0
CISA SSVC assessment
proof of concept public
19 Aug 202614:29 UTC, 24 hours after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade goshs.de/goshs/v2 to 2.1.0.

Affected software

Product	Affected	Fixed in
Gogoshs.de/goshs/v2	Affected <2.1.0	Fixed in 2.1.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

# WebDAV listener ignores `--read-only`, `--upload-only`, and `--no-delete` mode flags **Ecosystem:** Go **Package:** `goshs.de/goshs/v2` (`github.com/patrickhener/goshs`) **Affected:** `<= v2.0.9` (every release that ships the WebDAV handler) ## Summary When `goshs` is launched with WebDAV enabled (`-w`), the mode-restriction flags `--read-only`, `--upload-only`, and `--no-delete` are enforced only on the primary HTTP port. The WebDAV port is wired straight to `golang.org/x/net/webdav.Handler` with no equivalent guard, so an authenticated WebDAV client can `PUT`, `DELETE`, `MKCOL`, `MOVE`, and `COPY` despite the operator's stated intent. ## Details [`httpserver/server.go:207-238`](https://github.com/patrickhener/goshs/blob/v2.0.9/httpserver/server.go#L207-L238) — the WebDAV mux registers only `IPWhitelistMiddleware`, `ServerHeaderMiddleware`, and optionally `BasicAuthMiddleware`. There is no `fs.ReadOnly || fs.UploadOnly || fs.NoDelete` check on the WebDAV path. The HTTP mux in the same file (lines 134-204) does check these flags on every state-changing route. ## Proof of concept ```bash mkdir -p /tmp/r && echo secret > /tmp/r/x.txt goshs -p 18000 -wp 18001 -w -ro -d /tmp/r -b admin:pw & curl -u admin:pw -X PUT http://localhost:18000/y.txt --data x # 403 (HTTP enforces -ro) curl -u admin:pw -X PUT http://localhost:18001/y.txt --data x # 201 (WebDAV writes anyway) curl -u admin:pw -X DELETE http://localhost:18001/x.txt # 204 (WebDAV deletes anyway) curl -u admin:pw -X MKCOL http://localhost:18001/pwned/ # 201 (WebDAV creates dir) ``` ## Impact - **Integrity** — `--read-only` and `--no-delete` are silently downgraded to "no protection" on the WebDAV port. Any WebDAV client (curl, cadaver, Windows Explorer, Finder) can overwrite/delete files. - **Confidentiality** — `--upload-only` is also bypassed: WebDAV GET/PROPFIND still return file contents. - **Trust** — operators using `goshs -w -ro -d /srv/case-files -b reviewer:pw` to deliver engagement artifacts believe the directory is immutable. It isn't. ## Suggested fix Add a small `http.HandlerFunc` in front of `wdHandler` that maps WebDAV verbs to the existing mode flags: ```go wdGuard := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { switch r.Method { case http.MethodPut, "MKCOL", "MOVE", "COPY": if fs.ReadOnly || fs.UploadOnly { http.Error(w, "read-only", 403); return } case http.MethodDelete: if fs.ReadOnly || fs.UploadOnly || fs.NoDelete { http.Error(w, "delete disabled", 403); return } case http.MethodGet, "PROPFIND", "HEAD": if fs.UploadOnly { http.Error(w, "upload-only", 403); return } } wdHandler.ServeHTTP(w, r) }) ``` Add regression tests in `integration/functions.go` covering each mode flag × each WebDAV verb. Reporter: Nishant Verma. Reproduced live against `goshs v2.0.9` (commit `8fc1e91`) on 2026-05-27.

CWE-284Improper Access Control (opens in a new tab)
Pillar weaknessCWE Top 25 (2025): #19OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Operation
Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
Architecture and Design · Separation of Privilege
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
OWASP Cheat Sheets
Docker Security (opens in a new tab)
Third Party Javascript Management (opens in a new tab)
Virtual Patching (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V1.4.4 (opens in a new tab)
V1.4.5 (opens in a new tab)
V1.10.1 (opens in a new tab)
Attack patterns
Embedding Scripts within Scripts (opens in a new tab)
Modification of Windows Service Configuration (opens in a new tab)
Malicious Root Certificate (opens in a new tab)
Intent Spoof (opens in a new tab)
WebView Exposure (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Affected software

Description

WeaknessesCWE-284

Technical details

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