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CVE-2026-68120
rtase: Workaround for TX hang caused by hardware packet parsing
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-68120 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixed | 6.12.101-1 | Update the kernel and reboot. Fixed in 6.12.101-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The hardware performs packet parsing before packet transmission. Parsing incomplete IPv4, IPv6, TCP, or UDP headers may trigger a TX hang because the hardware parser expects additional protocol header data that is not present in the packet. The hardware performs additional PTP parsing on UDP packets identified by destination ports 319/320 at the expected UDP destination port offset. If such a packet has transport data smaller than RTASE_MIN_PAD_LEN, the hardware parser expects additional packet data and may trigger a TX hang. To avoid these hardware issues, the driver applies the following workarounds. Drop malformed packets that may trigger this hardware issue before transmission. For IPv4 non-initial fragments, the hardware does not check the fragment offset before parsing the expected transport header location. As a result, these packets are still subject to transport header parsing even though they do not contain a transport header. If the transport data is shorter than the minimum transport header required by the hardware parser, pad the transport data to the minimum transport header length required by the hardware parser. Packets that also match the hardware PTP parsing conditions continue to follow the corresponding workaround. For IPv6 fragmented packets, neither of the above hardware issues occurs because the hardware only continues packet parsing when the IPv6 Base Header Next Header field directly indicates UDP. Packets carrying a Fragment Header do not continue through the subsequent packet parsing stages. For packets identified for hardware PTP parsing, pad the transport data so it reaches RTASE_MIN_PAD_LEN before transmission.
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.
drivers/net/ethernet/realtek/rtase/rtase.h
drivers/net/ethernet/realtek/rtase/rtase_main.c
- What this is
- RTASE ETHERNET DRIVERMAINTAINERS section matched on drivers/net/ethernet/realtek/rtase/ · netdev@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_ETHERNET|CONFIG_NET_VENDOR_REALTEK|CONFIG_RTASE' /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 does not build this code in 4 releases. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixie, forky, sid, bookworm · linux-6.12n
- ?
- not established - no Makefile entry for the affected file
- n
- not enabled on any flavour - this release does not build the code
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switches
- CONFIG_ETHERNET, CONFIG_NET_VENDOR_REALTEK, CONFIG_RTASE
- 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
- 2026-08-10 (2 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.44%, higher than 36.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.12 | 6.12.101 | fe3a7320711e |
| 6.12 | 6.18.42 | 4a4f3aa6af20 |
| 6.12 | 7.1.6 | 0f54f5048615 |
| 6.12 | 7.2 | 1c50efa1faf3 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | 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 bug is in netdev TX; a remote attacker can send crafted IPv4 fragments or short PTP UDP (ports 319/320) that are forwarded/bridged out the rtase interface on automotive gateways and industrial routers, reaching rtase_start_xmit without local access.
- AC:LAttack complexity, low
- Trigger packets have well-defined shapes (non-initial IPv4 frags with short payload, malformed L3/L4 headers, or PTP UDP under 47 bytes) and the attacker controls generation, timing, and retries; no race or rare layout is required on affected hardware.
- PR:NPrivileges required, none
- Exploitation requires only the ability to inject network traffic that the host forwards or transmits via the rtase netdev; no target credentials, capabilities, or local shell access are needed on forwarding automotive/industrial gateways.
- UI:NUser interaction, none
- No victim interaction is required; the hang is triggered automatically when the kernel queues the crafted packet for transmission through the vulnerable NIC.
- S:UScope, unchanged
- Impact is confined to kernel/network availability on the host running the rtase driver; it does not cross VM, container, or IOMMU security boundaries.
- C:NConfidentiality impact, none
- The failure mode is a hardware TX parser hang with no memory corruption, out-of-bounds access, use-after-free, or information disclosure primitive.
- I:NIntegrity impact, none
- The vulnerability does not modify arbitrary data or enable code execution; it only stalls transmission until the netdev watchdog resets the interface.
- A:HAvailability impact, high
- Malformed TX packets can hang the NIC hardware transmit path, stopping egress and disrupting connectivity until rtase_tx_timeout invokes software reset; repeated injection enables sustained denial of service on safety-critical automotive networks.