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CVE-2026-70666
Lemur manages TLS certificate creation. Prior to 1.9.3, an authority-role member could update acme_url through PUT /api/1/authorities/ without revalidation and direct setup_acme_client_no_retry to an attacker-controlled ACME server. ACME directory and order responses contain newNonce, newOrder, authorizations, and finalize URLs chosen by that server. The Lemur ClientV2 followed those URLs without requiring their host to match the configured directory host, allowing JWS-signed requests to internal services or cloud metadata endpoints. The issue required an ACME authority and a user authorized for that authority, but did not require global administrator privileges. The fix revalidates updates and introduces _PinnedClientNetwork to enforce a single allowed host for the complete ACME flow. This issue is fixed in version 1.9.3.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data. There is a low impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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