# CVE-2026-104871: Angular SSR: Path Traversal to Sibling Directories in CommonEngine on Windows > An attacker can retrieve sibling prerendered HTML pages on Windows deployments with specific directory structures, exposing limited data. - **Severity:** Medium 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`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 2 Oct 2026 - **Updated:** 2 Oct 2026 - **Also known as:** CLSA-2026-1791302781, CLSA-2026-1791320260, CLSA-2026-1791320540, CLSA-2026-1791320698, CLSA-2026-1791322653, CLSA-2026-1792163463, CLSA-2026-1792163464, CLSA-2026-1792163465, CLSA-2026-1792163466, CLSA-2026-1792163467, CLSA-2026-1792202609, CLSA-2026-1792202610, CLSA-2026-1792202611, CLSA-2026-1792202612, CLSA-2026-1792248409, CLSA-2026-1792248410, CLSA-2026-1792248411, CLSA-2026-1792248412, CLSA-2026-1792279536, CLSA-2026-1792279537, CLSA-2026-1792279538, CLSA-2026-1792279539, CLSA-2026-1792279540, CLSA-2026-1792327355, CLSA-2026-1792327356, CLSA-2026-1792327357, CLSA-2026-1792327358, CLSA-2026-1792339037, CLSA-2026-1792339038, CLSA-2026-1792339039, CLSA-2026-1792339040, CLSA-2026-1792339041, CLSA-2026-1792348155, CLSA-2026-1792348156, CLSA-2026-1792348157, CLSA-2026-1792348158, CLSA-2026-1792348159, CLSA-2026-1792358885, CLSA-2026-1792358886, CLSA-2026-1792358887, CLSA-2026-1792358888, CLSA-2026-1792364766, CLSA-2026-1792364767, CLSA-2026-1792364768, CLSA-2026-1792364769, CLSA-2026-1792364771, GHSA-7g7c-h8rr-7p6q ## What is CVE-2026-104871? CVE-2026-104871 is a medium-severity path traversal vulnerability in angular-cli, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description 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. Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) ## Which versions are affected by CVE-2026-104871? 8 open source packages ship an affected version, including @angular/ssr. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `@angular/ssr` | npm | All versions to 19.2.27 | None | | `@angular/ssr` | npm | All versions to 19.2.27 | None | | `@angular/ssr` | npm | From 20.0.0 | 20.3.36 | | `@angular/ssr` | npm | From 20.0.0 | 20.3.36 | | `@angular/ssr` | npm | From 21.0.0 | 21.2.23 | | `@angular/ssr` | npm | From 21.0.0 | 21.2.23 | | `@angular/ssr` | npm | From 22.0.0 | 22.1.7 | | `@angular/ssr` | npm | From 22.0.0 | 22.1.7 | ## How do I fix CVE-2026-104871? Upgrade @angular/ssr to a fixed version for your release line: 20.3.36, 21.2.23 or 22.1.7. ## Is CVE-2026-104871 being exploited? There is no known exploitation of CVE-2026-104871 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-104871 and fix it if it is affected. What it is: CVE-2026-104871 is a medium-severity path traversal vulnerability in angular-cli, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-104871 in the wild and no public exploit code. Affected packages and fixed versions: - @angular/ssr (npm): affected all versions up to 19.2.27; no fix listed - @angular/ssr (npm): affected all versions up to 19.2.27; no fix listed - @angular/ssr (npm): affected from 20.0.0; fixed in 20.3.36 - @angular/ssr (npm): affected from 20.0.0; fixed in 20.3.36 - @angular/ssr (npm): affected from 21.0.0; fixed in 21.2.23 - @angular/ssr (npm): affected from 21.0.0; fixed in 21.2.23 - @angular/ssr (npm): affected from 22.0.0; fixed in 22.1.7 - @angular/ssr (npm): affected from 22.0.0; fixed in 22.1.7 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-104871/ (Markdown: https://insights.sbomify.com/CVE-2026-104871/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104871 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104871 - OSV: https://osv.dev/vulnerability/CVE-2026-104871 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-104871/ Summaries are generated and may contain mistakes; the official description above is the record.