Angular SSR: Path Traversal to Sibling Directories in CommonEngine on Windows

published 2026-10-02 37 d ago modified 2026-10-06 33 d ago also GHSA-7g7c-h8rr-7p6q , EUVD-2026-91778

cvss: 6.3; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits: 0; none known

The Angular SSR is a server-rise rendering tool for Angular applications. Prior to versions 20.3.36, 21.2.23, and 22.1.7, the CommonEngine retrieveSSGPage prerendered-page retrieval logic in @angular/ssr/node, and in @angular/ssr for versions 17 through 18, accepts a relative request URL containing a backslash parent-traversal segment on Windows. The non-special resolve:// URL base preserves the backslash, path.join interprets it as a Windows separator, and the pagePath.startsWith(normalize(publicPath)) check incorrectly accepts a sibling output directory whose name shares the configured public-directory prefix. An unauthenticated requester can therefore retrieve a sibling prerendered HTML page when that page contains the Angular SSG marker. The issue is limited to Windows deployments that pass relative request URLs to CommonEngine.render, have a prefix-sharing sibling output directory, and contain qualifying prerendered Angular HTML; it does not provide arbitrary file read. This issue is fixed in versions 20.3.36, 21.2.23, and 22.1.7.

Patch / fix

fixed in 1 links 7

npm @angular/ssr 20.3.36, 21.2.23, 22.1.7

github.com/angular/angular-cli@645e41a commit
github.com/angular/angular-cli@70748ca commit
github.com/angular/angular-cli@bb72145 commit
github.com/angular/angular-cli@c3e5982 commit
github.com/angular/angular-cli/releases/tag/v20.3.36 release
github.com/angular/angular-cli/releases/tag/v21.2.23 release
github.com/angular/angular-cli/releases/tag/v22.1.7 release

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 37 d ago (2026-10-02)

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	6.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CNA	4.0	6.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/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

Affected packages

ecosystem	package	affected	fixed in
npm	@angular/ssr	>=22.0.0, <22.1.7 >=21.0.0, <21.2.23 >=20.0.0, <20.3.36 <=19.2.27	22.1.7 21.2.23 20.3.36

Affected products

angular angular-cli

Classification

Weakness

CWE-22 Improper Limitation of a Pathname to a Restricted Directory

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.

Summary