CVE-2026-71303

What it is

Lemur manages TLS certificate creation. Prior to 1.9.3, _validate_acme_url enforced ACME_DIRECTORY_HOST_ALLOWLIST when an authority was created, but PUT /api/1/authorities/ passed options to lemur/authorities/service.py without applying the same check. A user holding an authority role could replace the stored acme_url with an internal service or instance-metadata URL such as 169.254.169.254. The next issuance operation loaded that value and passed it to ClientV2.get_directory, causing an outbound request from the Lemur backend. This bypassed the creation-time mitigation for CVE-2026-55166 and could expose internal services or cloud metadata. The fix revalidates acme_url whenever authority options are updated. This issue is fixed in version 1.9.3.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-18 20:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-22 22:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 7.7 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-08-18 20:17 UTC

Last modified

2026-10-22 22:10 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-918 · Server-side request forgery

Record status

Deferred

Attack profile CVSS 3.1 · 7.7

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-71303.md and follow it. Check whether this project is affected by CVE-2026-71303. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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