CVE-2026-45709

MEDIUMPre-NVD 5.85.8
EchelonGraph scoreLOW confidence

This medium-severity CVE scores 5.8 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit probability: 0.0%, top 89% 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: cna:github_m, epss
5.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.8Exploit: NoneExposed: 0

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

Mailpit is an email testing tool and API for developers. The fix for GHSA-6jxm-fv7w-rw5j (CVE-2026-23845, "Server-Side Request Forgery (SSRF) via HTML Check API"), shipped in mailpit v1.28.3, hardened internal/htmlcheck/css.go::downloadCSSToBytes with a 5MB size cap, a text/css content-type check, login-info stripping in isValidURL, and an opt-in --block-remote-css-and-fonts config flag — but did not add the IP-filtering dialer that the same codebase already uses on the two sister SSRF endpoints (the proxy handler and link-check). Prior to version 1.30.0, internal/htmlcheck/css.go::newSafeHTTPClient is mis-named — it builds an http.Client whose Transport.DialContext calls net.Dialer.DialContext directly with no IP allowlisting. As a result, the SSRF originally reported by Bao Anh Phan still permits the server to dial loopback, private, link-local, and any other reserved/multicast range, provided the target replies with HTTP/200 and a content-type beginning with text/css. With redirect-following (CheckRedirect allows redirects to any isValidURL URL with no IP filter), an attacker-controlled public site can redirect mailpit's request into the private network without ever appearing in the email's HTML. In the default mailpit deploy (no UI auth, no SMTP auth, port 1025/8025 exposed), this is an unauthenticated, network-reachable SSRF triggered by sending an HTML email and then issuing one HTTP GET to /api/v1/message/{id}/html-check. Version 1.30.0 contains an updated fix.

CVSS v3
5.8
EG Score
5.8(low)
EPSS
13.0%
KEV
Not listed

Published

May 19, 2026

Last Modified

July 21, 2026

Advisory Details (2)

Auto-updated Jul 20, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github.
github Patch Available🟡 PoC Available

Incomplete fix for GHSA-6jxm-fv7w-rw5j: HTML check still permits SSRF to private/loopback/IMDS via missing IP-filter dialer · Advisory · axllent/mailpit · GitHub

https://github.com/axllent/mailpit/security/advisories/GHSA-j3fj-qppj-fmmc
github_release Patch Available

Release v1.30.0 (axllent/mailpit)

Patch available: axllent/mailpit v1.30.0

https://github.com/axllent/mailpit/releases/tag/v1.30.0

Vendor Advisories for CVE-2026-45709(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)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/axllent/mailpit—1.30.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 2× in last 7d / 2× 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. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-21 15:24 UTCEPSS rescore
  3. 2026-06-14 23:18 UTCEPSS rescore
  4. 2026-06-13 23:00 UTCEPSS rescore
  5. 2026-06-12 23:12 UTCEPSS rescore
  6. 2026-05-24 06:14 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-45709?
CVE-2026-45709 is a medium vulnerability published on May 19, 2026. Mailpit is an email testing tool and API for developers. The fix for GHSA-6jxm-fv7w-rw5j (CVE-2026-23845, "Server-Side Request Forgery (SSRF) via HTML Check API"), shipped in mailpit v1.28.3, hardened internal/htmlcheck/css.go::downloadCSSToBytes with a 5MB size cap, a text/css content-type check,…
When was CVE-2026-45709 disclosed?
CVE-2026-45709 was first published in the National Vulnerability Database on May 19, 2026, with the most recent update on July 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45709 actively exploited?
CVE-2026-45709 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 13.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-45709?
CVE-2026-45709 has a CVSS v3 base score of 5.8 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-45709?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45709, 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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