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Fencer Vulns
critical 9.8

CVE-2026-33511 json

pyload-ng: Authentication Bypass via Host Header Injection in ClickNLoad

published 2026-03-24 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-15001

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

pyLoad is a free and open-source download manager written in Python. From version 0.4.20 to before version 0.5.0b3.dev97, the local_check decorator in pyLoad's ClickNLoad feature can be bypassed by any remote attacker through HTTP Host header spoofing. This allows unauthenticated remote users to access localhost-restricted endpoints, enabling them to inject arbitrary downloads, write files to the storage directory, and execute JavaScript code. This issue has been patched in version 0.5.0b3.dev97.

Patch / fix

  • pyload-ng_project pyload-ng 0.5.0b3.dev97
  • pyload pyload 0.5.0b3.dev97

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/pyload/pyload/security/advisories/GHSA-g5j2-gxqh-x7pw referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.8 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:L/SA:N
CNA 4.0 8.8 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • pyload pyload

Classification

Weakness
  • CWE-639 Authorization Bypass Through User-Controlled Key

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.