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CVE-2026-63985
ethtool: eeprom: add more safeties to EEPROM Netlink fallback
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/ethtool. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-63985 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 | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The Netlink fallback path for reading module EEPROM (fallback_set_params()) validates that offset < eeprom_len, but does not check that offset + length stays within eeprom_len. The ioctl equivalent (ethtool_get_any_eeprom() in ioctl.c) has always enforced both bounds: if (eeprom.offset + eeprom.len > total_len) return -EINVAL; This could lead to surprises in both drivers and device FW. Add the missing offset + length validation to fallback_set_params(), mirroring the ioctl. Similarly - ethtool core in general, and ethtool_get_any_eeprom() in particular tries to zero-init all buffers passed to the drivers to avoid any extra work of zeroing things out. eeprom_fallback() uses a plain kmalloc(), change it to zalloc.
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/ethtool/eeprom.c
- What this is
- NETWORKING [ETHTOOL]MAINTAINERS section matched on net/ethtool/
Check it on the machine
grep -w CONFIG_ETHTOOL_NETLINK /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_ETHTOOL_NETLINK
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
- 2026-07-19 (3 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/ethtool
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.13 | 5.15.210 | 0e1826898312 |
| 5.13 | 6.1.176 | 6ed7ebe22e9c |
| 5.13 | 6.6.143 | 65674d2489a1 |
| 5.13 | 6.12.93 | d81376053a00 |
| 5.13 | 6.18.35 | fd0de51c54fa |
| 5.13 | 7.0.12 | 4fe1bc4b3603 |
| 5.13 | 7.1 | 67cfdd9210b9 |
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:LAttack vector, local
- Exploitation requires sending an ETHTOOL_MSG_MODULE_EEPROM_GET Netlink request to the kernel; this is a local syscall/interface path, not remote packet processing.
- AC:LAttack complexity, low
- An attacker with CAP_NET_ADMIN can deterministically craft page/offset/length values after querying module info, and only needs a netdev using the legacy fallback path (common on ice/ixgbe/i40e-class drivers without get_module_eeprom_by_page).
- PR:LPrivileges required, low
- The ethtool Netlink handler is registered with GENL_UNS_ADMIN_PERM, requiring CAP_NET_ADMIN in the caller's user namespace, which is obtainable via unprivileged user namespaces (e.g., unshare -Urn).
- UI:NUser interaction, none
- No victim interaction is required; the attacker triggers the malformed EEPROM read directly via Netlink.
- S:UScope, unchanged
- Impact remains within the kernel/driver/NIC security domain on the same host; this is not a VM escape or cross-authority boundary crossing.
- C:HConfidentiality impact, high
- The fallback path used kmalloc() instead of kzalloc(), allowing uninitialized kernel heap contents to be returned to userspace, and out-of-bounds offset+length values cause legacy drivers to read and return data from beyond the declared EEPROM region (NIC/module memory).
- I:HIntegrity impact, high
- The fix commit explicitly warns of "surprises in both drivers and device FW" from out-of-bounds EEPROM access; on datacenter/cloud NICs this can drive NIC or transceiver firmware into undefined states that alter device behavior beyond the intended read-only query.
- A:HAvailability impact, high
- Invalid EEPROM parameters passed to driver and device firmware can cause kernel driver errors, NIC firmware hangs/resets, or link loss on production servers with optical modules installed.