CVE-2026-55162
CVE-2026-55162 — Lemur: Post-authentication SSRF via certificate verification - attacker-controlled CRL and OCSP URLs in uploaded certificates
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.
Published Updated Sources: NVD, Netflix (CNA), GitHub, GitHub Security Advisory, SOCRadar CTI
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
0%
ahead of 0% of scored CVEs
CVSS base
6.3
medium
Remediation
The vendor's own words where we have them.
Upgrade lemur to 1.9.2 or later (pip advisory GHSA-54vg-pfh7-jq95).
First 24 hours
Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.
- Identify exposed assets running affected vendor/product/version combinations.
- Prioritize based on EPSS, PoC availability, and external exposure.
- Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.
Affected scope
Vendor, product and version as the advisories word them.
| Vendor | Product | Versions | Status |
|---|---|---|---|
| Netflix | lemur | < 1.9.2 | Vulnerable |
| pip | lemur | <= 1.9.1 | Vulnerable |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Availability
Low
Confidentiality
Low
Integrity
Low
Scope
Unchanged
Attack Complexity
Low
Attack Vector
Network
Privileges Req
Low
User Interaction
None
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 6.3 | CVSS 3.1 | medium | 2.8 | 3.4 | GitHub (CNA), Netflix (CNA), GHSA |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
What this weakness leads to
MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.
CWE-918 · Server-Side Request Forgery (SSRF)
- Read Application Data
- Execute Unauthorized Code or Commands::
Weakness & attack patterns
- CWE-918Server-Side Request Forgery (SSRF)
Inferred from the weakness class — not observed against this CVE.
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /certificates/verify.py, /api/1/certificates/upload.
- Prioritize edge telemetry for network-reachable lemur.
Timeline
What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.
- 2026
Added · CVSS 3.1 6.3 (AV:N)
Aug 18, 2026 · NVD
Initial · CVE published
Aug 18, 2026 · NVD
Added · GHSA-54vg-pfh7-jq95 published (medium)
Jun 25, 2026 · GitHub Security Advisory
Source activity
Readings a source repeats on a schedule, counted rather than listed.
- 2×ModifiedAug 18, 2026 · SOCRadar CTI
References
4 on the record
- github.com/Netflix/lemur/commit/733714a2b00b2f72c3d460e440770e46a3ea9d6a
Exploit, Third Party Advisory, Mitre, NIST
- github.com/Netflix/lemur/releases/tag/v1.9.2
Exploit, Third Party Advisory, Mitre, NIST
- github.com/Netflix/lemur/security/advisories/GHSA-54vg-pfh7-jq95
Exploit, Third Party Advisory, Mitre, NIST
- github.com/advisories/GHSA-54vg-pfh7-jq95
Exploit, Third Party Advisory
Elsewhere on this site
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record1
What should defenders know first?
CVE-2026-55162 is Lemur: Post-authentication SSRF via certificate verification - attacker-controlled CRL and OCSP URLs in uploaded certificates, a medium vulnerability affecting lemur from Netflix, pip. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-55162. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-55162. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 6.3 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.