Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Check feature (/api/v1/message/{ID}/html-check) is designed to analyze HTML emails for compatibility. During this process, the inlineRemoteCSS() function automatically downloads CSS files from external `` tags to inline them for testing. Version 1.28.3 fixes the issue.
CVE-2026-23845
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 68% 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).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EG Risk
- 49(Track)EG Risk 49/100SSVC: 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 computedSeverity75% × 45%Exploitation0% × 40%Automatability100% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 34%
- KEV
- Not listed
Published
January 19, 2026
Last Modified
June 17, 2026
Advisory Details (3)
Auto-updated Aug 2, 2026Server-Side Request Forgery (SSRF) via HTML Check API · Advisory · axllent/mailpit · GitHub
https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5jRelease v1.28.3 (axllent/mailpit)
Patch available: axllent/mailpit v1.28.3
https://github.com/axllent/mailpit/releases/tag/v1.28.3commit 1679a0aba592 (axllent/mailpit)
Fix landed in axllent/mailpit commit 1679a0aba592 — awaiting tagged release
https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfeAffected Packages
(1 across 1 ecosystem)
Go(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| github.com/axllent/mailpit | — | 1.28.3 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 6× in last 7d / 28× 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.
Showing the most recent 100 of 153 total refreshes for this CVE.
- 2026-09-11 14:52 UTCEPSS rescore
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- 2026-08-15 01:30 UTCEPSS rescore
- 2026-08-14 13:43 UTCEG score recompute
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- 2026-08-02 23:01 UTCEG score recompute▲ 1.70
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- 2026-07-23 09:49 UTCOSV refresh
- 2026-07-23 03:07 UTCEG score recompute
- 2026-07-22 14:08 UTCEPSS rescore
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- 2026-07-06 05:02 UTCOSV refresh
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- 2026-06-25 13:49 UTCEPSS rescore
Frequently asked(5)
What is CVE-2026-23845?
When was CVE-2026-23845 disclosed?
Is CVE-2026-23845 actively exploited?
What is the CVSS score of CVE-2026-23845?
How do I remediate CVE-2026-23845?
Dependency Blast Radius
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