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CVE-2026-45713— Mailpit: Unauthenticated remote memory-exhaustion DoS via unlimited SMTP DATA and /api/v1/send body sizes

Quick assessment

Affected
axllent mailpit
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

axllent mailpit是axllent个人开发者开源的一款邮件测试与调试工具。 Ralph Slooten Mailpit 1.30.0之前版本存在资源管理错误漏洞，该漏洞源于SMTP服务器和HTTP /api/v1/send端点未正确限制请求数据大小，导致网络可达的攻击者可发送任意大消息，造成内存消耗激增并可能触发OOM-kill。

CVSS 7.5 · High EPSS 0.61% · P48

Affected Version Matrix 1

VendorProduct Version RangeStatus
axllent mailpit < 1.30.0 affected
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I. Basic Information for CVE-2026-45713

Vulnerability Information
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Vulnerability Title
Mailpit: Unauthenticated remote memory-exhaustion DoS via unlimited SMTP DATA and /api/v1/send body sizes
Source: CVE Program / CVE List V5
Vulnerability Description
Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the Mailpit SMTP server has a Server.MaxSize int field that controls the maximum allowed DATA payload size, but the field is never assigned anywhere outside test code, leaving it at Go's zero value (0 ⇒ "no limit"). The same applies to the HTTP /api/v1/send endpoint, whose request body is decoded with json.NewDecoder(r.Body) and no http.MaxBytesReader. Because Mailpit's default listeners bind [::]:1025 (SMTP) and [::]:8025 (HTTP), with no authentication required on either, a single network-reachable attacker can push an arbitrarily large message into Mailpit and watch RAM consumption spike with a ~7-10× amplification factor (raw frame → enmime envelope tree → search-text index → zstd-encoded write to SQLite). Repeating the attack — or running it concurrently from multiple connections — drives the process to OOM-kill. Version 1.30.0 contains a patch.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
Ralph Slooten Mailpit 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
axllent mailpit是axllent个人开发者开源的一款邮件测试与调试工具。 Ralph Slooten Mailpit 1.30.0之前版本存在资源管理错误漏洞，该漏洞源于SMTP服务器和HTTP /api/v1/send端点未正确限制请求数据大小，导致网络可达的攻击者可发送任意大消息，造成内存消耗激增并可能触发OOM-kill。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
axllent mailpit < 1.30.0 -

II. Public POCs for CVE-2026-45713

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 6744 chars
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III. Intelligence Information for CVE-2026-45713

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Vendor Advisories for CVE-2026-45713 (1)

Vendor Pages for CVE-2026-45713 (1)

Same Patch Batch · axllent · 2026-07-20 · 5 CVEs total

CVE-2026-45712 5.9 MEDIUM Mailpit: Concurrent map read & write in proxy CSS rewriter - remote unauth crash (fatal er
CVE-2026-45711 5.9 MEDIUM Mailpit: Path traversal & arbitrary file write in mailpit dump --http via attacker-control
CVE-2026-45709 5.8 MEDIUM Mailpit has an incomplete fix for GHSA-6jxm: HTML check still permits SSRF to private/loop
CVE-2026-48824 5.3 MEDIUM Mailpit: Sibling-endpoint memory-exhaustion DoS via unbounded JSON body on /api/v1/message

IV. Related Vulnerabilities

Same product: mailpit
Same vendor: axllent
Same weakness: CWE-400

V. Comments for CVE-2026-45713

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