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Vulnerabilities CVE-2026-55162

CVE-2026-55162

Medium
Open
TLP:CLEAR

Lemur: Post-authentication SSRF via certificate verification - attacker-controlled CRL and OCSP URLs in uploaded certificates

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Description

Lemur manages TLS certificate creation. Prior to 1.9.2, lemur/certificates/verify.py accepted CRL Distribution Point and OCSP responder URLs from uploaded certificate extensions and used them in crl_verify and ocsp_verify without adequate destination validation. An authenticated operator could submit a certificate through POST /api/1/certificates/upload and cause verify_string to reach loopback, RFC1918, link-local, or instance-metadata destinations such as 169.254.169.254. The requests could probe internal services and create side effects from the Lemur host network position. The CRL path also used an unbounded cache, allowing attacker-controlled entries to persist and consume memory. The fix validates destinations, supports explicit trusted-host allowlists, and bounds the CRL cache. This issue is fixed in version 1.9.2.

Details

CVSS Score
6.3
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Confidence
90%
Published
Aug 18, 2026
Last Modified
Aug 18, 2026
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