twenty-server SSRF protection bypass via IPv4-mapped IPv6 address normalization

published 2026-05-05 6 mo ago modified 2026-07-24 3 mo ago also EUVD-2026-27452

cvss: 8.3; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits: 0; none known

Twenty is an open source CRM built with NestJS (Node.js). In versions 1.18.0 and earlier, the SSRF protection in twenty-server's SecureHttpClientService can be bypassed using IPv4-mapped IPv6 addresses in URL IP literals. Node.js's URL parser normalizes IPv4-mapped IPv6 addresses to compressed hex form (e.g., ::ffff:169.254.169.254 becomes ::ffff:a9fe:a9fe), but the isPrivateIp utility only recognizes the dotted-decimal notation. As a result, the hex form passes the SSRF check unchecked. Additionally, the socket lookup validation event does not fire for IP literal addresses, bypassing the second validation layer. An authenticated user can reach any internal IP, including cloud metadata endpoints, to exfiltrate credentials such as IAM keys.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 6 mo ago (2026-05-06)

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/twentyhq/twenty/security/advisories/GHSA-vrcj-hv2q-c58m referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
CNA	4.0	8.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

twentyhq twenty

Classification

Weakness

CWE-918 Server-Side Request Forgery

References

github.com /twentyhq/twenty/security/advisories/GHSA-vrcj-hv2q-c58m
exploit

Sources

CVE List CVE-2026-33975
NVD CVE-2026-33975

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary