# CVE-2026-5917 — libgit2

> As of 2026-08-12, CVE-2026-5917 is a CRITICAL-severity vulnerability in libgit2, CVSS v3.1 9.6, EPSS 0.8% (55.2th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-5917 as of 2026-08-12; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-08-12

## What is CVE-2026-5917?

libgit2 versions v0.27.0 through v1.9.0 built with the libssh2 SSH backend (USE_SSH=libssh2) contain a shell command injection vulnerability that allows remote attackers to execute arbitrary commands on an SSH server by supplying a repository path containing unescaped shell metacharacters such as single quotes, semicolons, or pipes. The gen_proto() function in ssh_libssh2.c inserts the repository path directly into a shell command string without escaping special characters before passing it to libssh2_channel_exec(), enabling an attacker to craft a malicious submodule URL in a .gitmodules file that, when processed during a recursive clone, causes the remote server's shell to interpret injected commands under the victim's SSH user account.

The record classifies CVE-2026-5917 under weakness class [CWE-78](https://intel.threadlinqs.com/cwe/CWE-78). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 55 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 9.6 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H`)
- **CVSS v4.0 base score:** 9.4 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **EPSS (FIRST):** 0.8% probability of exploitation in the next 30 days, higher than 55.2% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 7/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-08-11, last modified 2026-08-12

## Is CVE-2026-5917 being exploited?

It currently carries a trending score of 43 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **libgit2**: libgit2

## How to fix CVE-2026-5917

No vendor patch reference has been recorded for CVE-2026-5917 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-2026-5917

No threat campaign in the Threadlinqs corpus currently references CVE-2026-5917, 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, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-08-13. This product uses the NVD API but is not endorsed or certified by the NVD.

**Third-party advisory**

- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/libgit2-shell-command-injection-via-ssh-libssh2-backend)

**Issue tracking and product pages**

- [github.com — product](https://github.com/libgit2/libgit2)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-5917
Full detection coverage and IOCs for threats exploiting CVE-2026-5917 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp