CVE-2026-48858 ftp client PASV response IP not validated against control peer, enabling SSRF and FTP bounce attacks
A malicious FTP server can redirect the Erlang OTP client's data connection to arbitrary internal hosts, enabling SSRF and data exfiltration or modification.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48858?
CVE-2026-48858 is a medium-severity server-side request forgery vulnerability in Erlang OTP, published on 10 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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 29.0.2, OTP 28.5.0.2 and OTP 27.3.4.13, corresponding to inets from 5.10.4 before 7.0 and ftp from 1.0 before 1.2.6, 1.2.4.1 and 1.2.3.1.
Weakness: CWE-918
Which versions are affected by CVE-2026-48858?
It affects 3 products.
Products include Erlang Erlang\/Inets, Erlang Erlang\/Otp, Erlang Ftp.
How do I fix CVE-2026-48858?
Upgrade to a fixed version.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-48858 being exploited?
There is no known exploitation of CVE-2026-48858 in the wild and no public exploit code.
Other vulnerabilities in Erlang OTP
Sources
Also known as AZL-90117, DEBIAN-CVE-2026-48858, EEF-CVE-2026-48858, GHSA-24cv-hwgr-37fq, UBUNTU-CVE-2026-48858.