GHSA-6px9-j4qr-xfjw CVE-2026-29778 PYSEC-2026-121
pyLoad has an Arbitrary File Write via Path Traversal in edit_package()
- Severity
- 7.1 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.54%
- Chance of exploitation in the next 30 days. Higher than 45.34% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-23 Relative Path Traversal
- Fix
0.5.0b3.dev97- Upgrade pyload-ng to this version or later
Description
The edit_package() function implements insufficient sanitization for the pack_folder parameter. The current protection relies on a single-pass string replacement of "../", which can be bypassed using crafted recursive traversal sequences.
Exploitation
An authenticated user with MODIFY permission can bypass the sanitization by submitting a payload such as:
pack_folder=..././..././..././tmp
After the single-pass replacement, this becomes:
../../../tmp
Because the traversal sequences are not properly validated, the resulting normalized path escapes the intended storage directory and writes files to /tmp or other locations.
Affected versions
PyPI
| Package | Vulnerable | Fixed in |
|---|---|---|
| pyload-ng | >= 0.5.0b3.dev13, < 0.5.0b3.dev97 |
0.5.0b3.dev97 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
pyload-ng PyPI → 0.5.0b3.dev97
- pip
pip install --upgrade "pyload-ng>=0.5.0b3.dev97"- poetry
poetry add "pyload-ng>=0.5.0b3.dev97"- uv
uv add "pyload-ng>=0.5.0b3.dev97"
Severity breakdown
CVSS 3.1 7.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- Low
Weakness
CWE-23: Relative Path Traversal
The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory.
How to prevent it
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
- Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked. Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes: realpath() in C getCanonicalPath() in Java GetFullPath() in ASP.NET realpath() or abs_path() in Perl realpath() in PHP
- Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-68w4-83fh-f2w8 pyload-ng: getUserData/get_userdata exposed at Perms.ANY allow any authenticated account to brute-force the administrator password | High | Also affects pyload-ng |
| GHSA-9q47-3cm2-2rp8 pyLoad: Rate-Limit Bypass and Audit-Log Spoofing via Trusted Client-Controlled `X-Forwarded-For` Header | Medium | Also affects pyload-ng |
| GHSA-jq7h-wrvp-3rgx pyLoad: Privilege revocation and password change through the REST API do not invalidate the user's session | High | Also affects pyload-ng |
| GHSA-889w-m37p-88m5 pyLoad: Api.set_user_permission never invalidates the target's session | High | Also affects pyload-ng |
| GHSA-p3pr-8f3m-4qp8 pyLoad WindowsPhoneNotify addon: non-admin SETTINGS user triggers SSRF via unguarded http.client notification host | Medium | Also affects pyload-ng |
| GHSA-fr26-jjhm-638c pyLoad: Tar extraction creates device nodes and FIFOs (member types not filtered; tarfile extractall without filter=) | High | Also affects pyload-ng |
| GHSA-r44w-v6gf-x3p6 pyLoad has an authentication bypass in API key validation (check_apikey cache) | High | Also affects pyload-ng |
| GHSA-j92p-c242-7hfx pyLoad: Unauthenticated access to /web/<path:filename> bypasses authentication on sensitive templates and leaks internal error details via exception attribute typo | Medium | Also affects pyload-ng |
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