CVE-2026-71272: Memos Webhook DNS Rebinding TOCTOU SSRF in safeDialContext()

Severity: high (CVSS 8.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-05 · updated 2026-10-24
Weakness: CWE-367

Description

Memos' webhook dispatch function safeDialContext (internal/webhook/webhook.go) resolves the target hostname via net.DefaultResolver.LookupHost and validates the resulting IPs against reserved ranges, but then dials net.JoinHostPort(host, port) using the original hostname rather than the already-validated IP address.

Affected products

usememos/memos: through 0.29.1

References

https://github.com/usememos/memos
https://github.com/usememos/memos/blob/main/internal/webhook/webhook.go

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