Atlassian Jira issue attachment name information disclosure vulnerability

Summary

An issue attachment name information disclosure vulnerability exists in Atlassian Jira, from versions 7.6.4 to 8.1.0. Anonymous users can differentiate between valid attachment names and invalid attachment names for any given issue via /rest/api/1.0/render API endpoint.

Tested Versions

Atlassian Jira 7.6.4 Atlassian Jira 8.1.0

Product URLs

<https://www.atlassian.com/software/jira&gt;

CVSSv3 Score

5.3 - CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CWE

CWE-862 - Missing Authorization

Details

An attacker can use this vector to identify valid attachment names for any given issue. This does not require a valid session.

Exploit Proof-of-Concept

Submit a POST to /rest/api/1.0/render with the following body:

{"rendererType":"atlassian-wiki-renderer",
"unrenderedMarkup":"!<ATTACHMENT-NAME>!",
"issueKey":"<ISSUE-KEY>"}

replacing <ISSUE-KEY> with a valid issue key, and <ATTACHMENT-NAME> with a possibly valid attachment name.

A response containing “Unable to render embedded object…” indicates the filename is not valid for the issue.
A response containing “Unable to embed resource…” or a link to the file like “…/secure/attachment/…” indicates the filename is valid.

Timeline

2019-05-14 - Vendor Disclosure
2019-09-09 - Vendor Patched
2019-09-16 - Public Release