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NVD / CVE Program· CNA Linux

CVE-2026-90078: net/sched: act_skbmod: fix length calculations and avoid invalid header warnings

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 0675cff3c2924eb9b80d9dd250cf56a1140af157, 1719865b20b22c88d2a55e922eff5ca31b0841f6, 62126464f3a6159c0a3dd89e196ba65bfeb0afc6; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1.

Low priority for now. Upgrade to Linux Linux 0675cff3c2924eb9b80d9dd250cf56a1140af157, 1719865b20b22c88d2a55e922eff5ca31b0841f6, 62126464f3a6159c0a3dd89e196ba65bfeb0afc6; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Sep 17, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 11th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.15affected
    • 56af5e749f20c3a540310c207dcc373f4f09156e and later · before 985a37781ade19061400100c2ba0f43979dd4d63affected · git
    • 56af5e749f20c3a540310c207dcc373f4f09156e and later · before d896843d8d925f0adbba319020595cfb1a7bcd57affected · git
    • 56af5e749f20c3a540310c207dcc373f4f09156e and later · before 0675cff3c2924eb9b80d9dd250cf56a1140af157affected · git
    • 56af5e749f20c3a540310c207dcc373f4f09156e and later · before e8a2027b7e686784a69b2dfcee841d779919f313affected · git
    • 56af5e749f20c3a540310c207dcc373f4f09156e and later · before 1719865b20b22c88d2a55e922eff5ca31b0841f6affected · git
    • 56af5e749f20c3a540310c207dcc373f4f09156e and later · before 62126464f3a6159c0a3dd89e196ba65bfeb0afc6affected · git
    • 56af5e749f20c3a540310c207dcc373f4f09156e and later · before 81d0d1e64f30d9989c829c0953cd6e6c68d9c5fbaffected · git
    • before 5.15not affected · semver
    • 5.15.221 and later · up to and including 5.15.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-90076Sep 17, 2026 · net/sched: fq: add overflow bounds to quantum and initial quantum
    0Monitor
  • ← EarlierCVE-2026-90077Sep 17, 2026 · net: fix a resource leak in copy_net_ns() error handling path
    0Monitor
  • Later →CVE-2026-90079Sep 17, 2026 · octeontx2-af: fix cn20k mailbox lifetime on repeated rvu_mbox_init()
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0675cff3c2924eb9b80d9dd250cf56a1140af157Vendor (CNA)
Linux Linux1719865b20b22c88d2a55e922eff5ca31b0841f6Vendor (CNA)
Linux Linux62126464f3a6159c0a3dd89e196ba65bfeb0afc6Vendor (CNA)
Linux Linux81d0d1e64f30d9989c829c0953cd6e6c68d9c5fbVendor (CNA)
Linux Linux985a37781ade19061400100c2ba0f43979dd4d63Vendor (CNA)
Linux Linuxd896843d8d925f0adbba319020595cfb1a7bcd57Vendor (CNA)
Linux Linuxe8a2027b7e686784a69b2dfcee841d779919f313Vendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records