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CVE-2026-98853
net: gso: limit recursive IP-in-IP segmentation
Published 2026-10-18 (today) by the Linux kernel CNA. Subsystem include/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-98853 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.2.10-1 | Update the kernel and reboot. Fixed in 7.2.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.10-1 | Update the kernel and reboot. Fixed in 7.2.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
IP-in-IP GSO can re-enter inet_gso_segment() or ipv6_gso_segment() for each nested IP header. encap_level tracks header bytes, not callback depth, so a deep chain can exhaust the kernel stack. Making inet_gso_segment() stackable introduced unbounded IPv4 nesting; IPIP GSO/TSO later made the path reachable. The IPv6 stackable path was introduced separately and uses the same guard. Count IPv4 and IPv6 GSO handler entries in skb_gso_cb, initialized once per top-level GSO operation and preserved across GRE/UDP context changes. Use the existing IP_TUNNEL_RECURSION_LIMIT for both handlers. The first five entries pass, and the sixth returns -EINVAL before dispatching another GSO callback.
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.
include/net/gso.h
net/core/gso.c
net/ipv4/af_inet.c
net/ipv6/ip6_offload.c
- What this is
- NETWORKING [GENERAL]MAINTAINERS section matched on include/net/ · netdev@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_INET /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.
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_INET
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
- 2026-10-18 (today)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- not scored
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- include/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 3.13 | 7.2.10 | c949646c900e |
| 3.13 | 7.3 | 006c8b834aed |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-98853, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.