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CVE-2026-90141
ipvs: fix integer overflow in ftp helper port/address parsing
Published 2026-09-17 (31 days ago) by the Linux kernel CNA. Subsystem net/netfilter. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-90141 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ip_vs_ftp_get_addrport() accumulates decimal digits into a __u16 (hport) and into unsigned char (p[]) without checking for overflow. A crafted FTP PASV/EPSV response with an over-long port or address octet wraps the value, so the helper configures the data connection with a truncated port/address. The netfilter conntrack FTP helper had the same defect, fixed in commit 2b413fc689ba ("netfilter: nf_conntrack_ftp: avoid u16 overflows"). Apply the equivalent fix here: widen the port accumulator to u32 and reject values above 65535, and reject address octets above 255.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/netfilter/ipvs/ip_vs_ftp.c
- What this is
- IPVSMAINTAINERS section matched on net/netfilter/ipvs/ · netdev@vger.kernel.org · Maintained
- Kernel module
- ip_vs_ftp
Check it on the machine
grep -wE 'CONFIG_IP_VS|CONFIG_IP_VS_FTP|CONFIG_NETFILTER' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ip_vs_ftpPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sid, bookworm · linux-6.12m
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_IP_VS, CONFIG_IP_VS_FTP, CONFIG_NETFILTER
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-17 (31 days ago)source
- CVSS
- 7.3 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Lsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.45%, higher than 37.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/netfilter
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 5.10.270 | d02de9a7a7e2 |
| 2.6.12 | 5.15.221 | fc1493c905d7 |
| 2.6.12 | 6.1.188 | 50cb9b7263a2 |
| 2.6.12 | 6.6.157 | deaa88fa010b |
| 2.6.12 | 6.12.110 | 00bcc6d67926 |
| 2.6.12 | 6.18.52 | 4aed450adaee |
| 2.6.12 | 7.2.6 | b1908bff0faa |
| 2.6.12 | 7.3 | e625a9477d12 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The wrap is in ip_vs_ftp_get_addrport() on decimal octets/port from the FTP TCP payload: client PORT/EPRT arrives via ip_vs_in_hook → ip_vs_nat_xmit → tcp_dnat_handler → ip_vs_ftp_in, and server PASV "227 "/EPSV "229 " via ip_vs_out_hook → tcp_snat_handler → ip_vs_ftp_out. FTP/TCP is a routable IP protocol.
- AC:LAttack complexity, low
- Each extra digit deterministically wraps: unsigned char p[i] is truncated on assignment, and __u16 hport wraps on hport*10+digit. After an IP_VS_TCP_S_ESTABLISHED NAT FTP control conn, a single crafted PORT/EPRT or 227/229 line is enough; there is no race or attacker-uncontrolled layout.
- PR:NPrivileges required, none
- tcp_app_conn_bind() attaches the ftp helper for MASQ conns to the app port (default 21) with no FTP USER/PASS check; ip_vs_ftp_in/ip_vs_ftp_out parse any established control payload. A remote peer that completes the TCP handshake to the IPVS VIP supplies the digits with no kernel credentials.
- UI:NUser interaction, none
- The attacker sends the PORT/EPRT command, or as the scheduled real server the PASV/EPSV reply, on a TCP session they already established; no other user must mount, open a file, or change IPVS configuration.
- S:UScope, unchanged
- ip_vs_conn_new(), ip_vs_tcp_conn_listen(), and ip_vs_nfct_expect_related() only change IPVS connection and netfilter expectation state on the load-balancer host; no VM, IOMMU, or guest-to-host boundary is crossed.
- C:LConfidentiality impact, low
- The truncated p[]/hport values become the data-connection tuple in ip_vs_conn_new(), and PASV/EPSV also calls ip_vs_nfct_expect_related() for a RELATED expectation on VIP:wrapped_port, so TCP to that port can be bound to the FTP session and its payload observed. This is not an arbitrary kernel read.
- I:LIntegrity impact, low
- ip_vs_ftp_in/ip_vs_ftp_out install the wrapped address/port via ip_vs_conn_new() and, for PASV/EPSV, rewrite the 227/229 text with nf_nat_mangle_tcp_packet() using n_cp->vport, so forwarding/NAT state describes a different endpoint than the peer sent. There is no OOB write or control-flow hijack.
- A:LAvailability impact, low
- ip_vs_tcp_conn_listen() parks the truncated-port conn in LISTEN, so the FTP data transfer fails and SYNs to that VIP port can be claimed instead of another virtual service until the conn times out. The parser does not oops, panic, or loop.