CVE-2026-63990 — bonding: refuse to enslave CAN devices
In the Linux kernel, the following vulnerability has been resolved: bonding: refuse to enslave CAN devices syzbot reported a kernel paging request crash in can_rx_unregister() inside net/can/af_can.c. The crash occurs because a virtual CAN device (vxcan) is being enslaved to a bonding master. During the enslavement process, the bonding driver mutates and modifies the network device states to fit an Ethernet-like aggregation model. However, CAN devices operate on a completely different Layer 2 architecture, relying on the CAN mid-layer private data structure (can_ml_priv) instead of standard Ethernet structures. Since bonding does not initialize or maintain these CAN structures, subsequent operations on the half-enslaved interface (such as closing associated sockets via isotp_release) lead to a null-pointer dereference when accessing the CAN receiver lists. Bonding CAN interfaces is architecturally invalid as CAN lacks MAC addresses, ARP capabilities, and standard Ethernet link-layer mechanisms. While generic loopback devices are blocked globally in net/core/dev.c, virtual CAN devices bypass this check because they do not carry the IFF_LOOPBACK flag, despite acting as local software-loopbacks. Fix this by explicitly blocking network devices of type ARPHRD_CAN from being enslaved at the very beginning of bond_enslave(). This prevents illegal state mutations, eliminates the resulting KASAN crashes, and avoids potential memory leaks from incomplete socket cleanups. As the CAN support has been added a long time after bonding the Fixes-tag points to the introduction of ARPHRD_CAN that would have needed a specific handling in bonding_main.c.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.1% (30-day exploitation probability)+0
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux | version 2.6.25≥ cd05acfe65ed2cf2db683fa9a6adb8d35635263b and < 8ba68464e4787b6a7ec938826e16124df20fd23d≥ cd05acfe65ed2cf2db683fa9a6adb8d35635263b and < 563090e5d450c665f70d955a39f9587afc7842eb≥ cd05acfe65ed2cf2db683fa9a6adb8d35635263b and < 9ea8a648d9120f7652bcde1ce2c4ad66871af707≥ cd05acfe65ed2cf2db683fa9a6adb8d35635263b and < 02f1c87ded33b43d48b4a1d665da15f2157b30d8≥ cd05acfe65ed2cf2db683fa9a6adb8d35635263b and < f4d78a81f57df82e9d82a2c07471fed1a1235893≥ cd05acfe65ed2cf2db683fa9a6adb8d35635263b and < 41e8478c4cd896d3abbe33d41afc90c84ac66602≥ cd05acfe65ed2cf2db683fa9a6adb8d35635263b and < 69b78b5f3033272e53a2dc2dad675962654a5b38 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel |
version 7.1-rc4version 7.1-rc5≥ 2.6.25 and < 5.15.210version 7.1-rc3version 7.1-rc2version 7.1-rc1≥ 6.19 and < 7.0.12≥ 6.13 and < 6.18.35 and 3 more≥ 6.7 and < 6.12.93≥ 6.2 and < 6.6.143≥ 5.16 and < 6.1.176 |
Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 5.5 | CVSS 3.1 | Medium | 1.8 | 3.6 | nvd@nist.gov via NIST National Vulnerability Database |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 16, 2026 · 4 reading(s) · max 0.13%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- Record published
- Fix documented
- CVSS changed · 5.5
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
7 on the record
- git.kernel.org/stable/c/41e8478c4cd896d3abbe33d41afc90c84ac66602
- git.kernel.org/stable/c/9ea8a648d9120f7652bcde1ce2c4ad66871af707
- git.kernel.org/stable/c/563090e5d450c665f70d955a39f9587afc7842eb
- git.kernel.org/stable/c/f4d78a81f57df82e9d82a2c07471fed1a1235893
- git.kernel.org/stable/c/69b78b5f3033272e53a2dc2dad675962654a5b38
- git.kernel.org/stable/c/02f1c87ded33b43d48b4a1d665da15f2157b30d8
- git.kernel.org/stable/c/8ba68464e4787b6a7ec938826e16124df20fd23d
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 2d
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 2d
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 3d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 3d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 3d
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 3d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-63990 is "bonding: refuse to enslave CAN devices", rated Medium. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.13% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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