CVE-2026-90078
Received
Received - Intake
BaseFortify
Vulnerability report for CVE-2026-90078, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-17
Last updated on: 2026-09-17
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
net/sched: act_skbmod: fix length calculations and avoid invalid header warnings
syzbot reported a warning in skb_network_header_len() triggered
by tcf_skbmod_act():
!skb_transport_header_was_set(skb)
WARNING: CPU: 0 PID: 14949 at include/linux/skbuff.h:3243 skb_network_header_len include/linux/skbuff.h:3243 [inline]
WARNING: CPU: 0 PID: 14949 at net/sched/act_skbmod.c:55 tcf_skbmod_act+0xfe8/0x1810 net/sched/act_skbmod.c:55
There are a few issues in tcf_skbmod_act():
1. Calling skb_network_header_len() assumes skb->transport_header is set,
which is not guaranteed when tcf_skbmod_act() runs at TC ingress.
2. Unconditionally calling skb_mac_header_len() at the beginning of
tcf_skbmod_act() triggers a warning on L3 devices (e.g. TUN) where the
MAC header is unset, evaluating to an underflowed garbage length.
3. On TC ingress, skb->data points to the network header. Adding the MAC
header length to the IP header length causes skb_ensure_writable() to
request more bytes than the actual IP packet length, dropping valid
short packets (e.g. 28-byte UDP/IPv4 packets).
Fix these by:
- Using skb_network_offset(skb) + sizeof(struct iphdr/ipv6hdr) for
SKBMOD_F_ECN so that the required length is correctly calculated on
both ingress (offset == 0) and egress (offset == mac_len).
- Setting max_edit_len to ETH_HLEN for Ethernet header modifications
after validating ARPHRD_ETHER.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
