# CVE-2025-15265: Svelte 5.46.0 - Hydratable Key Script-Breakout XSS (SSR)

> Attackers can inject arbitrary JavaScript via unescaped keys in Svelte SSR hydration, leading to remote code execution and account compromise.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA: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:** 15 Jan 2026
- **Updated:** 15 Jan 2026
- **Also known as:** GHSA-6738-r8g5-qwp3

## What is CVE-2025-15265?

CVE-2025-15265 is a medium-severity cross-site scripting vulnerability in Svelte, published on 15 Jan 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

An SSR XSS exists in async hydration when attacker‑controlled keys are passed to hydratable. The key is embedded inside a <script> block without HTML‑safe escaping, allowing </script> to terminate the script and inject arbitrary JavaScript. This enables remote script execution in users' browsers, with potential for session theft and account compromise.
This issue affects Svelte: from 5.46.0 before 5.46.3.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2025-15265?

2 open source packages ship an affected version, including svelte. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `svelte` | npm | From 5.46.0 | 5.46.4 |
| `svelte` | npm | From 5.46.0 | 5.46.4 |

Products: Svelte Svelte.

## How do I fix CVE-2025-15265?

Upgrade svelte to 5.46.4 or later.

## Is CVE-2025-15265 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-15265 exists.

## Other vulnerabilities in Svelte

- [CVE-2021-29261](https://insights.sbomify.com/CVE-2021-29261/): Code injection in n/a (high 7.8)
- [CVE-2026-42567](https://insights.sbomify.com/CVE-2026-42567/): Svelte: ReDoS in `<svelte:element>` Tag Validation (medium 5.9)
- [CVE-2024-45047](https://insights.sbomify.com/CVE-2024-45047/): Potential mXSS vulnerability due to improper HTML escaping in svelte (medium 5.4)
- [CVE-2022-25875](https://insights.sbomify.com/CVE-2022-25875/): Cross-site Scripting (XSS) (medium 5.4)
- [CVE-2026-42573](https://insights.sbomify.com/CVE-2026-42573/): Svelte: XSS via DOM Clobbering of Internal Framework State (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-15265 and fix it if it is affected.

What it is: CVE-2025-15265 is a medium-severity cross-site scripting vulnerability in Svelte, published on 15 Jan 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-2025-15265 exists.

Affected packages and fixed versions:
- svelte (npm): affected from 5.46.0; fixed in 5.46.4
- svelte (npm): affected from 5.46.0; fixed in 5.46.4

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-2025-15265/ (Markdown: https://insights.sbomify.com/CVE-2025-15265/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-15265
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-15265
- OSV: https://osv.dev/vulnerability/CVE-2025-15265

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-15265/
Summaries are generated and may contain mistakes; the official description above is the record.