Skip to content
Noroxi
NVD / CVE Program· CNA GitHub_M

CVE-2026-48737: pyLoad: SSRF guard bypass via IPv6 6to4/NAT64 transition wrappers of internal IPs

Noroxi assessment

Priority: Monitor (action score 19/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.28% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: pyload pyload 0.5.0b3.dev101.

Low priority for now. Upgrade to pyload pyload 0.5.0b3.dev101 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev101, is_global_address in src/pyload/core/utils/web/check.py relies on Python's global-address classification without examining IPv4 destinations embedded in 6to4 or NAT64 IPv6 addresses. A low-privileged user can submit an IPv6 literal through parse_urls to the pre-resolution is_global_host guard. Because host_to_ip is pinned to AF_INET, that guard does not evaluate a hostname's AAAA result. Separately, curl resolves hostnames before the pycurl PREREQFUNC in src/pyload/core/network/http/http_request.py applies the same vulnerable is_global_address check to the actual connection address, so a transition-form AAAA result can be permitted even when it terminates at an embedded loopback, private, CGNAT, or link-local IPv4 address. Exploitation requires the pyLoad host to route the applicable transition mechanism, including 6to4 on affected Python 3.9 through 3.11 deployments or NAT64 on a network with a NAT64 gateway. Successful exploitation can enable internal-network reconnaissance, timing-based confirmation, limited service disruption, or cloud metadata disclosure where the wrapped address is routable. This issue is fixed in version 0.5.0b3.dev101.

MediumCVSS 4.9 · v3.1—No exploit Fix available
Published
Sep 15, 2026
Updated
Sep 16, 2026
EPSS
0.2% · 21th percentile

Report tools

JSON

Action score

19

Monitor

Low priority for now.

CVSS
19 / 40 · 4.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.9
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-48737

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for pyload records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • pyload pyload

    • < 0.5.0b3.dev101affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
PyPIpyload-ngup to and including 0.5.0b3.dev100—

Same product

pyload: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-0297Code Injection in pyload/pyload
    68This week
  • CVE-2024-21644pyLoad unauthenticated flask configuration leakage
    43Plan
  • CVE-2025-53890pyLoad vulnerable to remote code execution through js2py onCaptchaResult
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-45348May 28, 2026 · pyLoad: Stored XSS in Downloads view via unsanitized link URL in packages.js template literal
    34Monitor
  • ← EarlierCVE-2026-46561May 28, 2026 · pyLoad: SSRF via HTTP Redirect Bypass in parse_urls API
    20Monitor
  • Later →CVE-2026-48987Sep 15, 2026 · pyLoad: Unbounded Memory Growth Leading to DoS and Potential DDoS in EventManager
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
pyload pyload0.5.0b3.dev101 · descriptionVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-33992172 days apartpyLoad: Server-Side Request Forgery via Download Link Submission Enables Cloud Metadata Exfiltration
    37Monitor
  • CVE-2026-46561110 days apartpyLoad: SSRF via HTTP Redirect Bypass in parse_urls API
    20Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-7559724 days apartpyLoad: Unauthenticated access to /web/<path:filename> bypasses authentication on sensitive templates and leaks internal error details via exception attribute t
    21Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
low · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
Low
Integrity impact
None
Availability impact
Low

Weakness class (CWE)

CWE-918 · Server-Side Request Forgery (SSRF)

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records