# 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.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Jun 2026
- **Updated:** 24 Jul 2026
- **Also known as:** AZL-90117, DEBIAN-CVE-2026-48858, EEF-CVE-2026-48858, GHSA-24cv-hwgr-37fq, UBUNTU-CVE-2026-48858

## 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 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-48858?

It affects 3 products.


Products: Erlang Erlang\/Inets, Erlang Erlang\/Otp, Erlang Ftp.

## How do I fix CVE-2026-48858?

Upgrade to a fixed version.

## 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

- [CVE-2026-28808](https://insights.sbomify.com/CVE-2026-28808/): ScriptAlias CGI targets bypass directory auth in inets httpd (mod_auth vs mod_cgi path mismatch) (high 8.3)
- [CVE-2026-48856](https://insights.sbomify.com/CVE-2026-48856/): httpc leaks Authorization header to cross-origin redirect targets (high 7.1)
- [CVE-2026-23941](https://insights.sbomify.com/CVE-2026-23941/): Request smuggling via first-wins Content-Length parsing in inets httpd (high 7.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48858 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-48858 in the wild and no public exploit code.

Affected product: Erlang OTP. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-48858/ (Markdown: https://insights.sbomify.com/CVE-2026-48858/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48858
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48858
- OSV: https://osv.dev/vulnerability/CVE-2026-48858

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48858/
Summaries are generated and may contain mistakes; the official description above is the record.