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CVE.org (no NVD analysis yet)· CNA GitHub_M

CVE-2026-118659: @happy-dom/server-renderer: ServerRendererServer Target-Origin Bypass SSRF / Open Proxy

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.39% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: capricorn86 happy-dom 21.0.2.

Low priority for now. Upgrade to capricorn86 happy-dom 21.0.2 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

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Prior to 21.0.2, the Happy DOM server-renderer package's ServerRendererServer accepts unauthenticated HTTP/2 requests and resolves attacker-controlled :path values against server.targetOrigin in #onIncomingRequest in packages/@happy-dom/server-renderer/src/ServerRendererServer.ts without confirming that the resolved origin remains trusted before calling fetch. A protocol-relative path can change the destination to an arbitrary HTTP or HTTPS endpoint reachable by the server, including local and internal services, and the proxy relays the fetched response headers and body to the requester. This issue is fixed in version 21.0.2.

Published
Oct 28, 2026
Updated
Oct 29, 2026
EPSS
0.3% · 33th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
7.5
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-2026-118659

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

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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.

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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.

  • capricorn86 happy-dom

    • < 21.0.2affected

Same product

capricorn86: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-62410--disallow-code-generation-from-strings is not sufficient for isolating untrusted JavaScript in happy-dom
    37Monitor
  • CVE-2024-51757Fixes security vulnerability that allowed for server side code to be executed by a <script> tag
    37Monitor
  • CVE-2026-115895Happy DOM: Incomplete fix for CVE-2026-33943: unsanitized import alias leads to host code execution
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2025-61927Oct 10, 2025 · Happy-DOM has VM Context Escape
    28Monitor
  • Later →CVE-2026-118660Oct 28, 2026 · Happy DOM: SSRF via iframe and link stylesheet when parsing untrusted HTML
    34Monitor
  • Later →CVE-2026-118661Oct 28, 2026 · Happy DOM: Cookie scope forgery: no DNS-label boundary on Domain= matching , attacker origin sets victim cookies
    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
capricorn86 happy-dom21.0.2 · 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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 13, 2026+16 d
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.

Variant candidates

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

  • CVE-2026-1186600 days apartHappy DOM: SSRF via iframe and link stylesheet when parsing untrusted HTML
    34Monitor

Not on record for this CVE: researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

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

CVSS vector

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

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. SSVC exploitation— → poc
  2. Exploit maturity— → none
  3. Fix✗ → ✓

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

References

Show all references (3 more)

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

All records