Answer in brief
CVE-2026-90078 records a Unknown severity vulnerability in net/sched: act_skbmod: fix length calculations and avoid invalid header warnings. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=56af5e749f20c3a540310c207dcc373f4f09156e <985a37781ade19061400100c2ba0f43979dd4d63 || >=56af5e749f20c3a540310c207dcc373f4f09156e <d896843d8d925f0adbba319020595cfb1a7bcd57 || >=56af5e749f20c3a540310c207dcc373f4f09156e <0675cff3c2924eb9b80d9dd250cf56a1140af157 || >=56af5e749f20c3a540310c207dcc373f4f09156e <e8a2027b7e686784a69b2dfcee841d779919f313 || >=56af5e749f20c3a540310c207dcc373f4f09156e <1719865b20b22c88d2a55e922eff5ca31b0841f6 || >=56af5e749f20c3a540310c207dcc373f4f09156e <62126464f3a6159c0a3dd89e196ba65bfeb0afc6 || >=56af5e749f20c3a540310c207dcc373f4f09156e <81d0d1e64f30d9989c829c0953cd6e6c68d9c5fb | 985a37781ade19061400100c2ba0f43979dd4d63, d896843d8d925f0adbba319020595cfb1a7bcd57, 0675cff3c2924eb9b80d9dd250cf56a1140af157, e8a2027b7e686784a69b2dfcee841d779919f313, 1719865b20b22c88d2a55e922eff5ca31b0841f6, 62126464f3a6159c0a3dd89e196ba65bfeb0afc6, 81d0d1e64f30d9989c829c0953cd6e6c68d9c5fb |
| Linux/Linuxgeneric | 5.15 | Not reported |
Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 17, 2026
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.
Quoted source text, attributed separately from HOL analysis.