Security Digest · Vulnerability record
CVE-2026-35459: pyLoad: SSRF filter bypass via HTTP redirect in BaseDownloader (Incomplete fix for CVE-2026-33992)
pyLoad is a free and open-source download manager written in Python.
CVSS 9.3 Critical EPSS 0.4% · p31
Should you act?
Critical, preconditions apply
Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.4%, percentile 31: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 31% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes
pyload-ng(PyPI) <= 0.5.0b3.dev96, no fixed version listed. Check your lockfile, including transitive dependencies.
What it is
pyLoad is a free and open-source download manager written in Python. In 0.5.0b3.dev96 and earlier, pyLoad has a server-side request forgery (SSRF) vulnerability. The fix for CVE-2026-33992 added IP validation to BaseDownloader.download() that checks the hostname of the initial download URL. However, pycurl is configured with FOLLOWLOCATION=1 and MAXREDIRS=10, causing it to automatically follow HTTP redirects. Redirect targets are never validated against the SSRF filter. An authenticated user with ADD permission can bypass the SSRF fix by submitting a URL that redirects to an internal address.
From the GitHub advisory
Summary
The fix for CVE-2026-33992 (GHSA-m74m-f7cr-432x) added IP validation to BaseDownloader.download() that checks the hostname of the initial download URL. However, pycurl is configured with FOLLOWLOCATION=1 and MAXREDIRS=10, causing it to automatically follow HTTP redirects. Redirect targets are never validated against the SSRF filter.
An authenticated user with ADD permission can bypass the SSRF fix by submitting a URL that redirects to an internal address.
Root Cause
The SSRF check at src/pyload/plugins/base/downloader.py:335-341 validates only the initial URL:
Weakness type: CWE-918.
Product: pyload-ng (PyPI) · Assigned by: GitHub_M · Published: 2026-04-06
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| PyPI | pyload-ng | <= 0.5.0b3.dev96 | none listed |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| pyload | pyload | <= 0.5.0b3.dev96 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 4.0 | 9.3 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N |
| CISA-ADP | 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| GitHub | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: low (any account)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.38% probability of exploitation activity in the next 30 days; percentile 31.
Timeline
- — GitHub-reviewed advisory GHSA-7gvf-3w72-p2pg published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-7gvf-3w72-p2pg github.com
- CVE.org record CVE-2026-35459 cve.org
- NVD entry CVE-2026-35459 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- nvd.nist.gov nvd.nist.gov