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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-98954: net: always dissect GSO packets in __virtio_net_hdr_to_skb()

—No exploit Fix available

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: 0.17% (FIRST EPSS).
  • Fixed version: Linux Linux 4.15, 4.20, 4.21; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 4.15, 4.20, 4.21; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes 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: always dissect GSO packets in __virtio_net_hdr_to_skb() Commit 9e8db5913264 ("net: avoid false positives in untrusted gso validation") added a '&& skb->network_header' check before flow-dissecting GSO packets without VIRTIO_NET_HDR_F_NEEDS_CSUM in __virtio_net_hdr_to_skb(), because some callers (such as tun_get_user(), tun_xdp_one(), virtnet_receive_done(), and raw_verify_header()) called virtio_net_hdr_*_to_skb() before initializing skb->network_header and skb->dev. Because __alloc_skb() and __build_skb_around() zero-initialize skb->network_header to 0 (unlike mac_header and transport_header which are initialized to ~0U), those four callers always had skb->network_header == 0 and bypassed flow dissection in __virtio_net_hdr_to_skb(). More generally, skb->network_header is an offset from skb->head (where 0 is also a valid offset whenever skb_headroom(skb) is 0), not a boolean flag. Whenever the 'if (gso_type && skb->network_header)' branch was skipped, the fallback 'else if (gso_type)' only pulled nh_min_len + thlen (40 bytes for TCPv4) without dissecting the packet, without validating ip_proto or n_proto, and without setting skb->transport_header. If the packet has a malformed network header, it is not rejected and a subsequent skb_probe_transport_header() also fails, leaving skb->transport_header at ~0U (0xffff). Similarly, if an IPv4 packet carries IP options (ihl > 5) or an IPv6 packet carries extension headers, pulling only nh_min_len + thlen can leave the TCP header outside skb->head. In both cases, tcp_hdrlen(skb) in skb_gso_transport_seglen() reads out-of-bounds: BUG: KASAN: slab-out-of-bounds in skb_gso_transport_seglen Read of size 2 by task poc/133 skb_gso_transport_seglen (net/core/gso.c:155) skb_gso_validate_mac_len (net/core/gso.c:270) tbf_enqueue (net/sched/sch_tbf.c:260) dev_qdisc_enqueue (net/core/dev.c:4227) __dev_queue_xmit (net/core/dev.c:4884) In addition, checking virtio_net_hdr_match_proto() only inside 'if (!skb->protocol)' before flow dissection both skipped validation when skb->protocol was pre-set by the caller and rejected VLAN-tagged frames whose outer L2 protocol is ETH_P_8021Q or ETH_P_8021AD. Fix this by: 1. Initializing skb->dev and skb->network_header (plus skb->protocol for IFF_TUN) before virtio_net_hdr_*_to_skb() in tun_get_user(), tun_xdp_one(), virtnet_receive_done(), and raw_verify_header(). In tun_get_user(), drop the redundant skb_reset_mac_header(skb) in the IFF_TUN case since __virtio_net_hdr_to_skb() unconditionally resets mac_header. 2. Removing '&& skb->network_header' and the unvalidated 'else if (gso_type)' fallback in __virtio_net_hdr_to_skb() so all GSO packets without VIRTIO_NET_HDR_F_NEEDS_CSUM are flow-dissected, have their transport header pulled into linear data, and have skb->transport_header set. 3. Moving the virtio_net_hdr_match_proto() check to after skb_flow_dissect_flow_keys_basic(), validating keys.basic.n_proto against hdr_gso_type.

Published
Oct 23, 2026
Updated
Oct 23, 2026
EPSS
0.1% · 6th percentile
CWE
—

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Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

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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.

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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

    • dac7d4432b13d6b58923c1178b786bcda37c9e9e, e93384b12443c9bb6830b56b7d299beed432b865, f709f7b28d76de327373598a0fda9f916c36b5e6, d996573ebd5c528c613e90b7e7daa961d58fa16e, c375152be9dd9d6fbf6ae5ac8be337d0590f192a, 0dab7eb86ea06ce8c530785f1999948c6f223c96, ea3fb2ce5fa794d02135f5c079e05cd6fc3f545d, 54ef8243c3c8e90f1ea5792e6752e021a25c8eb3, 5.0affected
    • d5be7f632bad0f489879eed0ff4b99bd7fe0b74c and later · before 5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34caffected · git
    • d5be7f632bad0f489879eed0ff4b99bd7fe0b74c and later · before 44378d02c5aaae24b60a75fbbb539b4aa4db503daffected · git
    • 4.14.104 and later · before 4.15affected · semver
    • 4.19.26 and later · before 4.20affected · semver
    • 4.20.13 and later · before 4.21affected · semver
    • 4.14.226 and later · before 4.15affected · semver
    • 4.19.181 and later · before 4.20affected · semver
    • before 5.0not affected · semver
    • 7.2.11 and later · up to and including 7.2.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:14linuxbefore 7.2.11-17.2.11-1

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-2026-98952Oct 23, 2026 · pfcp: make sure the SEID is linear before reading it
    29Monitor
  • ← EarlierCVE-2026-98953Oct 23, 2026 · devlink: fix devlink_rel reference leak when notify work is pending
    0Monitor
  • Later →CVE-2026-98955Oct 23, 2026 · flow_dissector: avoid u16 truncation of skb->len when computing thoff
    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 Linux4.15Vendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux4.21Vendor (CNA)
Linux Linux44378d02c5aaae24b60a75fbbb539b4aa4db503dVendor (CNA)
Linux Linux5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34cVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.159.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.161.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux7.2.11-1 · Debian:14Package 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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 12, 2026+20 d
EPSS, last 120 days

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

Patch and commit links

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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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

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Technical details

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

Weakness class (CWE)

—

Attack context

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Change log

  1. Exploit maturity— → none
  2. Fix✗ → ✓

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References

Show all references (1 more)

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

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