CVE-2026-45019

HIGHPre-NVD 7.27.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 76% of all CVEs by exploit prediction. 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
Trending — 3 sources updated this week
7.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.2Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Chainlit is a Python framework for building production-ready conversational AI applications. From 2.4.0rc0 until 2.12.0, Chainlit deployments with features.mcp.enabled set to true in .chainlit/config.toml expose the POST /mcp endpoint without requiring authentication. For sse and streamable-http transports, ConnectSseMCPRequest and ConnectStreamableHttpMCPRequest in backend/chainlit/types.py accept a user-controlled url and optional headers dictionary without scheme validation, private-address filtering, or an allowlist. The connect_mcp handler in backend/chainlit/server.py passes these values to sse_client() or streamablehttp_client(), allowing the Chainlit server to make blind outbound requests to arbitrary internal or external services, including cloud metadata endpoints, with attacker-controlled Authorization and Cookie headers. The SSE URL sink has existed since 2.4.0rc0, while attacker-controlled header forwarding and streamable-http support were added in 2.6.4. The response is consumed internally and not returned, but the attacker can issue state-changing authenticated requests, discover internal services, scan ports, and probe metadata endpoints. This issue is fixed in version 2.12.0.

CVSS v3
7.2
EG Score
7.2(medium)
EG Risk
48(Track)
EG Risk 48/100SSVC: Track

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
Severity72% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
24%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 27, 2026

Advisory Details (3)

Auto-updated Aug 25, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_release.
github_release Patch Available

2.12.0

Patch available: Chainlit/chainlit 2.12.0

https://github.com/Chainlit/chainlit/releases/tag/2.12.0
generic🟡 PoC Available

chainlit/docs/security-advisory-2026-mcp.md at 2.12.0 · Chainlit/chainlit · GitHub

https://github.com/Chainlit/chainlit/blob/2.12.0/docs/security-advisory-2026-mcp.md#spl-2026-002--ssrf-via-mcp-streamable-http--sse
github Patch Available🟡 PoC Available

SSRF via MCP SSE and streamable-http transports allows unauthenticated internal network access · Advisory · Chainlit/chainlit · GitHub

https://github.com/Chainlit/chainlit/security/advisories/GHSA-hvfh-5mj3-5f3j

Vendor Advisories for CVE-2026-45019(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 rangeFixed inDependents
chainlit2.10.0 ... 2.9.6 (41 versions)2.12.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 12× 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. 2026-08-30 02:49 UTCEG score recompute
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-29 03:57 UTCEG score recompute
  4. 2026-08-28 21:41 UTCEPSS rescore
  5. 2026-08-27 17:34 UTCEG score recompute
  6. 2026-08-27 17:11 UTCEG score recompute
  7. 2026-08-27 14:25 UTCEPSS rescore
  8. 2026-08-26 19:13 UTCEG score recompute
  9. 2026-08-26 14:46 UTCEPSS rescore
  10. 2026-08-25 20:23 UTCEG score recompute
  11. 2026-08-25 19:35 UTCEG score recompute
  12. 2026-08-25 19:34 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-45019?
CVE-2026-45019 is a high vulnerability published on August 25, 2026. Chainlit is a Python framework for building production-ready conversational AI applications. From 2.4.0rc0 until 2.12.0, Chainlit deployments with features.mcp.enabled set to true in .chainlit/config.toml expose the POST /mcp endpoint without requiring authentication. For sse and streamable-http…
When was CVE-2026-45019 disclosed?
CVE-2026-45019 was first published in the National Vulnerability Database on August 25, 2026, with the most recent update on August 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45019 actively exploited?
CVE-2026-45019 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 75.7% of all scored CVEs.
What is the CVSS score of CVE-2026-45019?
CVE-2026-45019 has a CVSS v3 base score of 7.2 (NVD).
How do I remediate CVE-2026-45019?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45019, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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