VulnerabilityPublished 31 Jul 2026

CVE-2026-54707: Onionshare cli · OnionShare Receive mode writes uploaded files even when file uploads are disabled

Affects onionshare-cliSource GCVE Database

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Not known to be exploited · CVSS 5.4 Medium : upgrade to 2.6.4 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

5.4Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.6.4

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

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 31 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
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

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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 onionshare-cli to 2.6.4.

Affected software

Product	Affected	Fixed in
PyPIonionshare-cli	Affected <2.6.4	Fixed in 2.6.4

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AI-suggested

A patch is available in OnionShare version 2.6.4 that fixes this issue by properly enforcing the 'disable_files' setting at the file upload sink. Users should upgrade to version 2.6.4 or later to remediate this vulnerability. Until patched, users should avoid running the Receive mode with 'disable_files' enabled in environments where untrusted senders can reach the service. No other mitigations are documented or necessary once patched.

Description

### Summary OnionShare CLI/Desktop 2.6.3 does not enforce the Receive mode `disable_files` setting at the file upload sink. When a Receive service is configured as a text-message-only endpoint (`--disable-files` / "Disable uploading files"), a remote sender who can reach the OnionShare service can still send a crafted multipart request containing `file[]`; OnionShare writes the uploaded bytes to disk before the route handler skips file accounting. This affects the shipped `onionshare-cli` Python package and the desktop application because both use the same `onionshare_cli.web.receive_mode` request-streaming implementation. ### Details Tested repository: `https://github.com/onionshare/onionshare` at commit `8cc75e1d7e88bd31f7276733449d412bf71c8999`. Affected product evidence: - `cli/pyproject.toml` declares `onionshare_cli` version `2.6.3`. - `desktop/pyproject.toml` declares `onionshare` version `2.6.3` and depends on `onionshare_cli` from `../cli`. - `cli/setup.py` publishes `onionshare-cli` and includes `onionshare_cli.web` plus templates/static resources. - `desktop/setup.py` publishes `onionshare` and exposes both `onionshare` and `onionshare-cli` console scripts. Reachable default/common paths: - CLI Receive mode is exposed through `--receive` (`cli/onionshare_cli/__init__.py:55-57`). - The `--disable-files` option is documented and stored in mode settings (`cli/onionshare_cli/__init__.py:156-160`, `cli/onionshare_cli/__init__.py:254-261`). - Desktop Receive mode exposes the same setting via the "Disable uploading files" checkbox and stores it as `receive.disable_files` (`desktop/onionshare/tab/mode/receive_mode/__init__.py:89-99`, `desktop/onionshare/tab/mode/receive_mode/__init__.py:246-254`). - User documentation says "Disable uploading files" should "only allow submitting text messages, like for an anonymous contact form" (`docs/source/features.rst:64`). - Advanced documentation lists `--disable-files` and `disable_files` as the option to disable receiving files (`docs/source/advanced.rst:162-163`, `docs/source/advanced.rst:455`). Root cause: - The Receive template hides the file input when `disable_files` is set (`cli/onionshare_cli/resources/templates/receive.html:51-56`), but this is only UI-side. - The `/upload` route skips `request.files.getlist("file[]")` and file accounting when `disable_files` is enabled (`cli/onionshare_cli/web/receive_mode.py:96-135`). However, by this point Werkzeug has already parsed the multipart body and invoked the custom stream factory. - `ReceiveModeRequest.__init__()` treats every `POST /upload` or `POST /upload-ajax` as an upload request and creates a receive directory regardless of `disable_files` (`cli/onionshare_cli/web/receive_mode.py:369-391`). - `ReceiveModeRequest._get_file_stream()` creates a writable `ReceiveModeFile` for each uploaded part without checking `self.web.settings.get("receive", "disable_files")` (`cli/onionshare_cli/web/receive_mode.py:517-540`). - `ReceiveModeFile` opens `<receive_mode_dir>/<secure_filename>.part`, writes attacker-controlled bytes, then renames the `.part` file to the final filename (`cli/onionshare_cli/web/receive_mode.py:272-285`, `cli/onionshare_cli/web/receive_mode.py:320-346`). False-positive screening performed: - `secure_filename()` is used at `cli/onionshare_cli/web/receive_mode.py:111-113` and `cli/onionshare_cli/web/receive_mode.py:527-528`, so the confirmed issue is not path traversal; the file is written under the configured receive data directory. - The UI hiding the file input is bypassable by direct multipart POST. - Route-level `if not disable_files` only affects later accounting/status/webhook behavior; it does not prevent the stream sink from creating and writing the file. - Default non-public onion services require the sender to know the onion address and private key unless the user opts into public mode. This limits exposure but does not enforce the user-selected "text only" security policy for authorized senders or public contact-form deployments. - A control case with `disable_text=True` showed submitted text was not written as a message file, demonstrating the harness was exercising the settings boundary. Affected versions / patched versions: - Affected versions: unknown; confirmed in version `2.6.3` at commit `8cc75e1d7e88bd31f7276733449d412bf71c8999`. Earlier versions were not tested during this audit. - Patched versions: 2.6.4 Severity: Rationale: `AV:N` because the Receive endpoint is reached over the OnionShare HTTP service; `AC:L` because a crafted multipart POST is straightforward once the service is reachable; `PR:L` because the sender generally needs the OnionShare URL/private key unless the receiver intentionally runs public mode; `UI:N` because no further receiver interaction is required after service startup; `S:U` because the same local application writes the file; `C:N` because this PoC does not read data; `I:L` because the attacker writes unwanted files in a mode configured to

Impact

An attacker with access to the OnionShare Receive endpoint can upload arbitrary files even when file uploads are disabled, causing unwanted files to be written to the receiver's disk. This does not allow reading or modifying existing files, nor does it disclose data. The impact is limited to integrity (I:L) and availability (A:L) because the attacker can write files but cannot read data or execute code. The vulnerability requires knowledge of the OnionShare address and private key unless the service is run in public mode, limiting exposure. The severity is rated medium with a CVSS score of 5.4.

CWE-863Incorrect Authorization (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #17OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
Architecture and Design
Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
Architecture and Design
Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
V7.2.2 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 31 Jul 2026, 20:19 UTC

WeaknessesCWE-863

Technical details

References

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