MediumCVE-2026-118777

Forge: Prototype Pollution in forge.http cookie handling via a malicious Set-Cookie (CVE-2026-118777)

Published 29.10.2026Last modified 30.10.2026Sources: OSV, Hersteller, CVE.org

What is affected, what to do

Update Digitalbazaar Forge to version 1.4.1.

Affected: Digitalbazaar Forge lt *..1.4.1
Fixed in: Digitalbazaar Forge 1.4.1

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

4.8

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: Vendor (CNA), CVSS v3

4.8

CVSS v3

Severity Medium on the scale from 0 to 10.

Source: OSV, Hersteller, CVE.org

0.3 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 17.2

Show all metrics

Severity: Medium
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 56.36 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 4.8 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 4.8
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.3 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 17.2; Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 29.10.2026
CISA assessment (SSVC): Exploitation: none known · not automatable · Technical impact: partial; Source: CISA Vulnrichment, as of 30 October 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-1321

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Summary

The forge.http client stored cookies from Set-Cookie response headers in a plain object keyed by cookie name and path. A malicious server could use the cookie name __proto__ to add properties to Object.prototype, use inherited names such as constructor to add properties to Object, and send an empty cookie value to delete Object.prototype properties. Fixed in node-forge 1.4.1.

Details

client.setCookie() in lib/http.js stored a cookie with client.cookies[cookie.name][cookie.path] = cookie, creating client.cookies[cookie.name] only when !(cookie.name in client.cookies). Both values come from the server's Set-Cookie header via response.getCookies(). Because in also sees inherited properties:

a cookie named __proto__ skipped the initialization, client.cookies['__proto__'] returned Object.prototype, and the cookie path was written as a new Object.prototype property, visible on every object;
a cookie named constructor wrote onto the global Object function the same way;
a cookie with an empty value calls client.removeCookie(name, path), which used the same in checks and then delete client.cookies[name][path], so Set-Cookie: __proto__=; path=toString deleted Object.prototype.toString. This path skipped the cookie's secure-flag and domain checks, so it also worked for http:// clients.

forge.http is not loaded by require('node-forge'). It is included in the forge.all browser bundle and is used with a socket pool, for example by forge.xhr.

The fix uses own-property checks for the cookie store and ignores cookies named __proto__ or with the path __proto__.

Patches

Fixed in node-forge 1.4.1. Cookies from a server can no longer add or remove properties of Object.prototype or Object.

Workarounds

Don't use forge.http or forge.xhr with servers that aren't trusted, or filter Set-Cookie headers named __proto__, constructor or other Object.prototype property names before they reach the client.

Credits

Reported by @arunmozhivarman-dtx and @Dremig.

Proof of concept

A server response for a forge.http client (http.createClient({url: 'https://...', socketPool: ...})) containing:

Set-Cookie: __proto__=evil; path=polluted

On 1.4.0, after the client processes the response, ({}).polluted is the cookie object. With Set-Cookie: __proto__=; path=toLocaleString, Object.prototype.toLocaleString is deleted (for http:// and https:// clients). On 1.4.1 these cookies are ignored and Object.prototype is unchanged.

Regression tests are in tests/security/ghsa-6wvx-3r32-xmcg.js.

Impact

Applications that use the forge.http client (directly, or through forge.xhr in the forge.all browser bundle) against a server that can be malicious are affected. The server can add properties to Object.prototype and Object for the whole JavaScript realm, which can change application logic that reads properties from plain objects, and can delete built-in Object.prototype methods, breaking the page or process. Applications that don't use forge.http are not affected.

Source: OSV (Open Source Vulnerabilities), GitHub Security Advisories, cvelistv5, NVD (NIST)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
digitalbazaar	forge	`< 1.4.1`	`1.4.1`
npm	node-forge	`<= 1.4.0` `—`	`1.4.1` `1.4.1`

Vendors and products

Digitalbazaar Forge

Weakness classes (CWE)

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Variant
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
Entry at MITRE CWE-1321

References & sources

github.comdigitalbazaar/forge/commit/797c3f816a22748a96fceebb34eb3a671685…x_refsource_MISC, web
github.comdigitalbazaar/forge/releases/tag/v1.4.1x_refsource_MISC, web
github.comdigitalbazaar/forge/security/advisories/GHSA-6wvx-3r32-xmcgx_refsource_CONFIRM, web
NVD (NIST)vuln/detail/CVE-2026-118777advisory
github.comdigitalbazaar/forgepackage

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

30.10.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: none known, automatable: no

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
SSVC assessment	added	—	{"id":"CVE-2026-118777","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-30T15:20:36.875932Z"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

29.10.2026ReceivedGitHub

CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

Weakness type: CWE-1321

Description added or changed

New references:

Show 7 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	added	—	Forge (also called node-forge) is a native implementation of Transport Layer Security in JavaScript. Prior to 1.4.1, the forge.http client stored cookie names and paths from Set-Cookie response headers in ordinary JavaScript objects. A malicious server could use the cookie name __proto__ so that the attacker-controlled cookie path was written as a property on Object.prototype, or use inherited names such as constructor to modify Object. An empty cookie value could use the removal path to delete an inherited Object.prototype property. Applications using forge.http directly or through forge.xhr are affected; applications that do not use forge.http are unaffected. This issue is fixed in version 1.4.1.
CVSS	added	—	AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
Weakness type (CWE)	added	—	CWE-1321
Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/118xxx/CVE-2026-118777.json">CVE-2026-118777</a>
Reference	added	—	https://github.com/digitalbazaar/forge/commit/797c3f816a22748a96fceebb34eb3a6716853991
Reference	added	—	https://github.com/digitalbazaar/forge/releases/tag/v1.4.1
Reference	added	—	https://github.com/digitalbazaar/forge/security/advisories/GHSA-6wvx-3r32-xmcg

Source identifier: security-advisories@github.com

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