# PhpSpreadsheet: XmlScanner Bypass via Double-Encoded unentity() TOCTOU Allows XXE and Denial of Service Advisory record · `GHSA-rxj4-h86g-25gc` - **Identifiers:** `GHSA-rxj4-h86g-25gc` · `CVE-2026-108357` · `PKSA-zb3c-6qhx-m249` - **State:** Confirmed - **Severity:** CVSS 8.8 High - **Critical:** No - **Weakness (CWE):** [CWE-611](https://cwe.mitre.org/data/definitions/611.html) · [CWE-776](https://cwe.mitre.org/data/definitions/776.html) - **Tags:** [XML external entities (XXE)](https://agentprime.io/advisories/tag/xxe.md) · [Denial of service](https://agentprime.io/advisories/tag/dos.md) - **Published:** 27 Oct 2026 - **Updated:** 27 Oct 2026 - **Reviewed by a person:** No Published by the GitHub Advisory Database at 27 Oct 2026, 15:38 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `phpoffice/phpspreadsheet` (Packagist): affected `>=4.0.0, <5.10.0 || >=3.3.0, <3.10.8`; fixed in `5.10.0`, `3.10.8` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > PhpSpreadsheet versions 3.3.0 up to 3.10.8 and 4.0.0 up to 5.10.0 are affected. The SpreadsheetML XML reader can be tricked by a specially encoded file into skipping its check for XML declarations. An attacker who can get an application to process such a file can cause denial of service through entity expansion on all PHP versions, and can read local files or make server-side requests on PHP below 8.0 or when LIBXML_NOENT is used. Upgrade to 3.10.8 or 5.10.0, which contain fixes. Written 31 Oct 2026. ## Not analysed yet We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check. ## Severity and exploitation - 8.8 High, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:L/SI:N/SA:N`, from CNA (GitHub_M) - **CISA KEV:** Not listed. - **EPSS:** 0.0046, the 40th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline - 31 Oct 2026, 13:53 UTC: First seen by agentprime - 31 Oct 2026, 13:53 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-rxj4-h86g-25gc) ## Sources - [GitHub Advisory Database: GHSA-rxj4-h86g-25gc](https://github.com/advisories/GHSA-rxj4-h86g-25gc) - [OSV: GHSA-rxj4-h86g-25gc](https://osv.dev/vulnerability/GHSA-rxj4-h86g-25gc) - - - - - - - Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code. ## Check whether this affects you A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet. - With the agentprime MCP server (), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .