Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the screenshot/print proxy (/proxy?data=…) maintains a package-level assets map[string]MessageAssets cache, but reads the map without holding assetsMutex while a long-running cleanup goroutine and (re-entrant) CSS-rewriting code path concurrently write to it under the lock. When the unsynchronized read coincides with a synchronized write, Go's runtime raises fatal error: concurrent map read and map write — a runtime.throw that is not recoverable by http.Server's handler-panic recover. The whole Mailpit process exits, taking the SMTP, POP3 and HTTP listeners down with it. Version 1.30.0 contains a patch.
CVE-2026-45712
MEDIUMPre-NVD 5.95.9Elevated
EchelonGraph scoreLOW confidence
This medium-severity CVE scores 5.9 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 74% 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
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.9Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.9
- EG Score
- 5.9(low)
- EG Risk
- —
- EPSS
- 10.0%
- KEV
- Not listed
Published
May 19, 2026
Last Modified
July 21, 2026
Advisory Details (2)
Auto-updated Jul 21, 2026🔬 Proof of concept available. Patch available. Sources: github_release, github.
github Patch Available🟡 PoC Available
Concurrent map read & write in proxy CSS rewriter - remote unauth crash (fatal error: concurrent map read and map write) · Advisory · axllent/mailpit · GitHub
https://github.com/axllent/mailpit/security/advisories/GHSA-w4vj-r5pg-3722github_release Patch Available
Release v1.30.0 (axllent/mailpit)
Patch available: axllent/mailpit v1.30.0
https://github.com/axllent/mailpit/releases/tag/v1.30.0Vendor Advisories for CVE-2026-45712(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)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| github.com/axllent/mailpit | — | 1.30.0 | — |
Weakness Classification(2)
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.
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:24 UTCEPSS rescore
- 2026-06-14 23:18 UTCEPSS rescore
- 2026-06-13 23:00 UTCEPSS rescore
- 2026-06-12 23:12 UTCEPSS rescore
- 2026-05-24 06:14 UTCEG score recompute
Related CVEs(same CWE)
Same CWE
10 shownCWE-362 · CWE-770
Frequently asked(5)
What is CVE-2026-45712?
CVE-2026-45712 is a medium vulnerability published on May 19, 2026. Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the screenshot/print proxy (/proxy?data=…) maintains a package-level assets map[string]MessageAssets cache, but reads the map without holding assetsMutex while a long-running cleanup goroutine and (re-entrant)…
When was CVE-2026-45712 disclosed?
CVE-2026-45712 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-2026-45712 actively exploited?
CVE-2026-45712 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 10.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-45712?
CVE-2026-45712 has a CVSS v3 base score of 5.9 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-45712?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45712, 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
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-45712
Is Your Infrastructure Affected by CVE-2026-45712?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.