Memos Webhook DNS Rebinding TOCTOU SSRF in safeDialContext()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-71272
StatePUBLISHED
AssignerTuranSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-05 13:24:51 UTC
Updated2026-08-05 16:17:06 UTC
DescriptionMemos' 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. Because net.Dialer.DialContext() performs its own independent DNS resolution, an attacker controlling DNS for the webhook's hostname (e.g. via a short TTL) can return a public, allowed IP during validation and a different, internal IP at dial time — a classic time-of-check/time-of-use DNS-rebinding bypass of the SSRF protection.

Risk And Classification

Primary CVSS: v3.1 8.5 HIGH from 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Problem Types: CWE-367 | CWE-367 CWE-367

VersionSourceTypeScoreSeverityVector
3.1309f9ea4-e3e9-4c6c-b79d-e8eb01244f2cSecondary8.5HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
3.1CNADECLARED8.5HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Usememos Memos affected 0.29.1 semver Not specified

References

ReferenceSourceLinkTags
github.com/usememos/memos 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c github.com
github.com/usememos/memos/blob/main/internal/webhook/webhook.go 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Alibek Baxtiyorov (en)

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