# CVE-2026-59728: @astrojs/rss: XML Injection via Unescaped RSS Feed Fields > Attackers can inject malicious XML into RSS feeds via unescaped fields, corrupting feed structure and injecting false metadata for subscribers. - **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 27 Jul 2026 - **Updated:** 28 Jul 2026 - **Also known as:** CLSA-2026-1784596299, CLSA-2026-1784943236, CLSA-2026-1792161555, CLSA-2026-1792161559, CLSA-2026-1792161694, CLSA-2026-1792161701, CLSA-2026-1792161786, CLSA-2026-1792161789, CLSA-2026-1792161855, CLSA-2026-1793093746, CLSA-2026-1793093842, GHSA-8j5q-mfj2-5q9q ## What is CVE-2026-59728? CVE-2026-59728 is a medium-severity vulnerability in withastro astro, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link. ### Official description Astro is a web framework for content-driven websites. In versions 1.0.0 through 4.0.18, the source.title and enclosure.type item fields in packages/astro-rss/src/index.ts are interpolated directly into XML template strings without XML-character escaping before being parsed by fast-xml-parser. Both fields are validated only as z.string(), placing no restriction on XML special characters. An attacker who controls these values can inject arbitrary XML into the generated RSS feed: a value containing " can break out of an attribute (as with enclosure.type), and a value containing can close an element early and inject additional nodes (as with source.title). This corrupts feed structure, injects false metadata (for example, a fake pointing to a malicious URL), and can cause feed readers to misparse or display attacker-controlled content. In SSR mode (output: 'server'), the poisoned feed is served on every request to all subscribers. This issue has been fixed in version 4.0.19. Weakness: CWE-91 (XML Injection) ## Which versions are affected by CVE-2026-59728? 2 open source packages ship an affected version, including @astrojs/rss. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `@astrojs/rss` | npm | From 1.0.0 | 4.0.19 | | `@astrojs/rss` | npm | From 1.0.0 | 4.0.19 | ## How do I fix CVE-2026-59728? Upgrade @astrojs/rss to 4.0.19 or later. ## Is CVE-2026-59728 being exploited? It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59728 exists. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-59728 and fix it if it is affected. What it is: CVE-2026-59728 is a medium-severity vulnerability in withastro astro, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link. Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59728 exists. Affected packages and fixed versions: - @astrojs/rss (npm): affected from 1.0.0; fixed in 4.0.19 - @astrojs/rss (npm): affected from 1.0.0; fixed in 4.0.19 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-2026-59728/ (Markdown: https://insights.sbomify.com/CVE-2026-59728/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-59728 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-59728 - OSV: https://osv.dev/vulnerability/CVE-2026-59728 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-59728/ Summaries are generated and may contain mistakes; the official description above is the record.