CVE-2026-48858ftp client PASV response IP not validated against control peer, enabling SSRF and FTP bounce attacks

Description

Server-Side Request Forgery (SSRF) vulnerability in Erlang/OTP ftp (ftp_internal module) allows FTP bounce attacks and SSRF via an unvalidated PASV response IP address. The ftp_internal:handle_ctrl_result/2 PASV handler (mode=passive, ipfamily=inet, ftp_extension=false) extracts the IP address from the server's 227 response and passes it directly to gen_tcp:connect/4 without validating it against the control connection peer address. The adjacent EPSV handlers correctly call peername(CSock) to derive the IP from the control connection, but the PASV handler does not. A malicious or compromised FTP server can redirect the client's data connection to an arbitrary internal host and port. On read operations (ftp:ls/1,2, ftp:nlist/1,2, ftp:recv/2,3), data from the redirected target is returned to the caller. On write operations (ftp:send/2,3, ftp:append/2,3), file content is sent to the redirected target. This enables SSRF against internal hosts, cloud metadata endpoints, and FTP bounce attacks against third-party hosts. The vulnerable path is the default configuration (mode=passive, ipfamily=inet, ftp_extension=false). RFC 2577 section 3 explicitly recommends validating the PASV response IP against the control connection peer. The ftp application is deprecated and scheduled for removal in OTP-30. This vulnerability is associated with program files lib/inets/src/ftp/ftp_internal.erl (inets 5.10.4 through 6.5, OTP 17.4 through 20.3) and lib/ftp/src/ftp_internal.erl (ftp 1.0 and later, OTP 21.0 and later). This issue affects OTP from OTP 17.4 before OTP 27.3.4.13, OTP 28.5.0.2, and OTP 29.0.2, corresponding to inets from 5.10.4 before 7.0, and ftp from 1.0 before 1.2.3.1, 1.2.4.1, and 1.2.6.

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

References and patches

• FTP Client PASV Response IP not Validated Against Control Peer, Enabling SSRF and FTP Bounce Attacks vendor-advisoryrelatedMitigationVendor Advisory
• EEF CNA record for CVE-2026-48858 relatedMitigationThird Party Advisory
• OSV record EEF-CVE-2026-48858 relatedMitigationThird Party Advisory
• Erlang/OTP version ordering Product
• Introducing commit be95772 in erlang/otp related
• Fix commit 521bcfa in erlang/otp patchPatch
• Fix commit 2691a80 in erlang/otp patchPatch