# CVE-2026-93955 — grimmory-tools grimmory

> As of 2026-09-19, CVE-2026-93955 is a MEDIUM-severity vulnerability in grimmory-tools grimmory, CVSS v3.1 4.3, EPSS 0.3% (33.6th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-93955 as of 2026-09-19; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-19

## What is CVE-2026-93955?

A vulnerability was detected in grimmory-tools grimmory up to 3.3.3/3.4.1. Affected by this vulnerability is the function streamFileToResponse of the file backend/src/main/java/org/booklore/controller/KoboController.java of the component Download Endpoint. Performing a manipulation of the argument bookId results in authorization bypass. The attack may be initiated remotely. The exploit is now public and may be used. Issue #2431 is closed as completed, but its only comment states that the issue “has already been reported elsewhere.” No fixing commit or pull request is identified there.

The record classifies CVE-2026-93955 under weakness classes [CWE-639](https://intel.threadlinqs.com/cwe/CWE-639), [CWE-285](https://intel.threadlinqs.com/cwe/CWE-285). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 16 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 4.3 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:P/RL:X/RC:R`)
- **CVSS v4.0 base score:** 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 33.6% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-19

## Is CVE-2026-93955 being exploited?

It currently carries a trending score of 38 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **grimmory-tools**: grimmory

## How to fix CVE-2026-93955

No vendor patch reference has been recorded for CVE-2026-93955 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-93955

No threat campaign in the Threadlinqs corpus currently references CVE-2026-93955, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on 2026-09-20.

**Exploit and proof of concept**

- [github.com — exploit](https://github.com/grimmory-tools/grimmory/issues/2431)

**Technical analysis**

- [vuldb.com — vdb entry](https://vuldb.com/vuln/407914)

**Third-party advisory**

- [vuldb.com — signature](https://vuldb.com/vuln/407914/cti)
- [vuldb.com — third party advisory](https://vuldb.com/cve/CVE-2026-93955)
- [vuldb.com — third party advisory (943921)](https://vuldb.com/submit/943921)

**Issue tracking and product pages**

- [github.com — issue tracking](https://github.com/grimmory-tools/grimmory/issues/2431#issuecomment-5384402858)
- [github.com — product](https://github.com/grimmory-tools/grimmory/)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-93955
Full detection coverage and IOCs for threats exploiting CVE-2026-93955 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp