# CVE-2026-116802: DOMPurify before 3.4.17 XSS via SMIL attributeName Guard Bypass in XHTML Mode - **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`) - **Exploited in the wild:** Not known - **Fix available:** Yes - **Published:** 26 Oct 2026 - **Updated:** 26 Oct 2026 - **Also known as:** CLSA-2026-1792929353, CLSA-2026-1792929831, CLSA-2026-1792929955, CLSA-2026-1792930059, CLSA-2026-1792930172, CLSA-2026-1792930526, CLSA-2026-1792930630, CLSA-2026-1792930723, CLSA-2026-1792930826, CLSA-2026-1792930930, CLSA-2026-1792931034, CLSA-2026-1792931144, CLSA-2026-1792931242, CLSA-2026-1792931347, CLSA-2026-1792931454, CLSA-2026-1792931555, CLSA-2026-1792931687, CLSA-2026-1792931792, CLSA-2026-1792931903, CLSA-2026-1792932016, CLSA-2026-1792932134, CLSA-2026-1792932246, CLSA-2026-1792932377, CLSA-2026-1792932499, CLSA-2026-1792932612, CLSA-2026-1792932735, CLSA-2026-1792932854, CLSA-2026-1792932980, CLSA-2026-1792933104, CLSA-2026-1792933241, CLSA-2026-1792933812, CLSA-2026-1793130420, DEBIAN-CVE-2026-116802, ECHO-1770-aeeb-fed3, GHSA-c6gr-qvv4-5v3f, GHSA-g32m-chc6-3wqf, UBUNTU-CVE-2026-116802 ## What is CVE-2026-116802? CVE-2026-116802 is a medium-severity vulnerability in cure53 DOMPurify, published on 26 Oct 2026. ### Official description DOMPurify before 3.4.17 contains a cross-site scripting vulnerability that allows attackers to bypass the SMIL attributeName=href guard when PARSER_MEDIA_TYPE is application/xhtml+xml, because transformCaseFunc does not lowercase attribute names. Attackers can submit SVG with an animate or set element using attributeName="href" and a javascript: entry in values to execute script when users click the sanitized link. Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation) ## Which versions are affected by CVE-2026-116802? 2 open source packages ship an affected version, including dompurify. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `dompurify` | npm | All versions | 3.4.17 | | `dompurify` | npm | All versions | 3.4.17 | ## How do I fix CVE-2026-116802? Upgrade dompurify to 3.4.17 or later. ## Is CVE-2026-116802 being exploited? There is no known exploitation of CVE-2026-116802 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-116802 and fix it if it is affected. What it is: CVE-2026-116802 is a medium-severity vulnerability in cure53 DOMPurify, published on 26 Oct 2026. Exploitation: There is no known exploitation of CVE-2026-116802 in the wild and no public exploit code. Affected packages and fixed versions: - dompurify (npm): affected all versions; fixed in 3.4.17 - dompurify (npm): affected all versions; fixed in 3.4.17 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-2026-116802/ (Markdown: https://insights.sbomify.com/CVE-2026-116802/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-116802 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-116802 - OSV: https://osv.dev/vulnerability/CVE-2026-116802 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-116802/ Summaries are generated and may contain mistakes; the official description above is the record.