CVE-2026-71303

HIGHPre-NVD 7.77.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (18th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
7.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.7Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
7.7
EG Score
7.7HIGHmedium confidence
EG Risk
51
EG Risk 51/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity77% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
18th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 18, 2026

Last Modified

September 8, 2026

Advisory Details (3)

Auto-updated Aug 18, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

v1.9.3

Patch available: Netflix/lemur v1.9.3

https://github.com/Netflix/lemur/releases/tag/v1.9.3
github_commit Patch Available

commit edca0390f930 (Netflix/lemur)

Patch available: Netflix/lemur v1.9.3 (contains commit edca0390f930)

https://github.com/Netflix/lemur/commit/edca0390f930344d65ff4ca37a669c2320e3dfad
github Patch Available🟡 PoC Available

Incomplete fix for GHSA-v2wp-frmc-5q3v -- ACME authority update endpoint allows non-admin to replace `acme_url` with internal IP, bypassing allowlist · Advisory · Netflix/lemur · GitHub

https://github.com/Netflix/lemur/security/advisories/GHSA-v5rc-cpwc-cfpr

Vendor Advisories for CVE-2026-71303(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
lemur0.11.0 ... 1.9.2 (20 versions)
  • every version up to 1.9.3: fixed in 1.9.3
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 48× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-05 06:05 UTCEG score recompute
  2. 2026-10-04 23:22 UTCEPSS rescore
  3. 2026-10-03 17:37 UTCEG score recompute
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  10. 2026-09-30 15:03 UTCEPSS rescore
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  16. 2026-09-27 07:55 UTCEG score recompute
  17. 2026-09-26 15:59 UTCEPSS rescore
  18. 2026-09-25 01:25 UTCEG score recompute
  19. 2026-09-23 20:19 UTCEG score recompute
  20. 2026-09-23 17:54 UTCEPSS rescore
  21. 2026-09-22 20:24 UTCEG score recompute
  22. 2026-09-22 06:17 UTCEG score recompute
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  24. 2026-09-20 20:28 UTCEG score recompute
  25. 2026-09-20 20:16 UTCEPSS rescore
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  1. 2026-09-19 21:44 UTCEG score recompute
  2. 2026-09-18 23:21 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 01:41 UTCEG score recompute
  5. 2026-09-16 15:58 UTCEG score recompute
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 06:32 UTCEG score recompute
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-13 20:35 UTCEG score recompute
  11. 2026-09-12 22:55 UTCEG score recompute
  12. 2026-09-12 15:02 UTCEPSS rescore
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  14. 2026-09-11 14:53 UTCEPSS rescore
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  16. 2026-09-10 16:44 UTCEG score recompute
  17. 2026-09-10 09:35 UTCEPSS rescore
  18. 2026-09-09 08:06 UTCEG score recompute
  19. 2026-09-08 22:01 UTCEPSS rescore
  20. 2026-09-07 16:07 UTCEG score recompute
  21. 2026-09-06 14:24 UTCEG score recompute
  22. 2026-09-06 13:48 UTCEPSS rescore
  23. 2026-09-05 16:44 UTCEG score recompute
  24. 2026-09-04 19:00 UTCEG score recompute
  25. 2026-09-04 07:48 UTCEG score recompute
  26. 2026-09-04 05:07 UTCEPSS rescore
  27. 2026-09-02 21:56 UTCEG score recompute
  28. 2026-09-02 14:12 UTCEPSS rescore
  29. 2026-09-01 20:15 UTCEG score recompute
  30. 2026-09-01 13:54 UTCEPSS rescore
  31. 2026-08-30 23:15 UTCEG score recompute
  32. 2026-08-30 19:17 UTCEPSS rescore
  33. 2026-08-30 01:28 UTCEG score recompute
  34. 2026-08-30 01:22 UTCEPSS rescore
  35. 2026-08-29 03:46 UTCEG score recompute
  36. 2026-08-28 21:42 UTCEPSS rescore
  37. 2026-08-27 21:11 UTCEG score recompute
  38. 2026-08-26 23:32 UTCEG score recompute
  39. 2026-08-26 14:47 UTCEPSS rescore
  40. 2026-08-25 15:03 UTCEG score recompute
  41. 2026-08-25 13:49 UTCEPSS rescore
  42. 2026-08-24 17:23 UTCEG score recompute
  43. 2026-08-23 08:53 UTCEG score recompute
  44. 2026-08-23 00:19 UTCEPSS rescore
  45. 2026-08-22 00:23 UTCEG score recompute
  46. 2026-08-21 23:49 UTCEPSS rescore
  47. 2026-08-21 02:43 UTCEG score recompute
  48. 2026-08-20 22:56 UTCEPSS rescore
  49. 2026-08-19 18:14 UTCEG score recompute
  50. 2026-08-19 17:04 UTCEPSS rescore
  51. 2026-08-19 07:14 UTCEG score recompute
  52. 2026-08-18 20:22 UTCEG score recompute
  53. 2026-08-18 19:53 UTCEG score recompute
  54. 2026-08-18 19:19 UTCEG score recompute
  55. 2026-08-18 19:18 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-71303?
CVE-2026-71303 is a high vulnerability published on August 18, 2026. Lemur manages TLS certificate creation. Prior to 1.9.3, validateacmeurl enforced ACMEDIRECTORYHOSTALLOWLIST 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…
When was CVE-2026-71303 disclosed?
CVE-2026-71303 was first published on August 18, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-71303 actively exploited?
CVE-2026-71303 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (18th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-71303?
CVE-2026-71303 has a CVSS base score of 7.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-71303?
A fix for CVE-2026-71303 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-71303 are linked in the Vendor Advisories panel on this page.

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