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

CVE-2026-98852: net: extend IPv6 exthdr detection of tunneled packets

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: 0.15% (FIRST EPSS).
  • Fixed version: Linux Linux 44ba9dc568c878b699d05e7cf699572dc9df4b59, 5f0764cb1c81a9712bce605d38efe6d844a70b29, 6.12.113; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1.

Low priority for now. Upgrade to Linux Linux 44ba9dc568c878b699d05e7cf699572dc9df4b59, 5f0764cb1c81a9712bce605d38efe6d844a70b29, 6.12.113; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1 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: extend IPv6 exthdr detection of tunneled packets Commit c4336a07eb6b ("net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback") split skb_gso_has_extension_hdr() into mutually exclusive branches on skb->encapsulation. This did not yet address all paths: 1. With skb->encapsulation set, the outer header is not checked. IPv6 tunnels such as ip6_gre and ip6_tunnel add an outer Destination Options header by default (encap_limit). Their GSO packets skip software GSO, then skb_csum_hwoffload_help() sees the outer extension header and calls skb_checksum_help() on the GSO skb, which warns and drops it. 2. Tunnels over IPv6 without an outer transport header, such as ip6_tunnel, leave skb->transport_header at the inner transport header. skb_network_header_len() then spans the outer IPv6, tunnel and inner IP headers, a false positive. 3. UDP tunnels without an inner network header, such as SCTP-in-UDP or PSP, have no inner IPv6 header to check. Decide on the outer header alone. 4. Directly dereferencing inner_ip_hdr(skb)->version without skb_header_pointer() is unsafe. Instead, check ipv6_ext_hdr(nexthdr) on the outer IPv6 header and, if set, on the inner IPv6 header. Read the headers with skb_header_pointer(). Keep the skb_network_header_len() check when !skb->encapsulation to also catch encapsulated packets without skb->encapsulation (e.g., virtio). Use the same helper in skb_csum_hwoffload_help(). Its open coded test has the false positive of (2) and ignores the inner header. Background: checksum offload of tunneled packets invariants: Non-GSO skb: - If the inner packet is CHECKSUM_PARTIAL, Local Checksum Offload computes the outer checksum in software and the device offloads only the inner L4 checksum. - If the inner packet is CHECKSUM_NONE (e.g., SCTP-in-UDP, ESP-in-UDP, Remote Checksum Offload), the device offloads the outer UDP or GRE checksum instead. GSO skb: - A device with NETIF_F_GSO_UDP_TUNNEL_CSUM or NETIF_F_GSO_GRE_CSUM computes both inner and outer checksums per segment. The outer checksum is seeded with only the pseudo-header checksum. A NETIF_F_IPV6_CSUM device must parse through the outer headers to reach the inner ones.

—No exploit Fix available
Published
Oct 18, 2026
Updated
Oct 21, 2026
EPSS
0.1% · 4th 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 · 0.1%

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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

    • 2094a7cf91b71367b649f991aacc7b579f793d0b, 732fdeb2987c94b439d51f5cb9addddc2fc48c42, 7.0affected
    • ed71cf465c75f5688b07a35d373cd1d6b589c8ea and later · before fdbd83c2d929ec968b37d2f75149a79440e328ffaffected · git
    • 33670f780e0120c3dacda188c512bbffe0b6044c and later · before 44ba9dc568c878b699d05e7cf699572dc9df4b59affected · git
    • a98b78116a27e2a57b696b569b2cb431c95cf9b6 and later · before aa480f05aed7a9eee87d4a6fc90647fe9679c670affected · git
    • c4336a07eb6b2526dc2b62928b5104b41a7f81f5 and later · before cabacdf98e09eb74599c4d97d7bd7fd659598fb7affected · git
    • c4336a07eb6b2526dc2b62928b5104b41a7f81f5 and later · before 5f0764cb1c81a9712bce605d38efe6d844a70b29affected · git
    • 6.6.134 and later · before 6.6.160affected · semver
    • 6.12.81 and later · before 6.12.113affected · semver
    • 6.18.22 and later · before 6.18.56affected · semver
    • 6.1.168 and later · before 6.2affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.113-1~deb12u16.12.113-1~deb12u1
Debian:13linuxbefore 6.12.113-16.12.113-1
Debian:14linuxbefore 7.2.10-17.2.10-1

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-2026-98850Oct 18, 2026 · net/packet: prevent TX_RING byte count overflow
    0Monitor
  • ← EarlierCVE-2026-98851Oct 18, 2026 · netfilter: nft_flow_offload: drop flowtable reference on init error path
    0Monitor
  • Later →CVE-2026-98853Oct 18, 2026 · net: gso: limit recursive IP-in-IP segmentation
    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 Linux44ba9dc568c878b699d05e7cf699572dc9df4b59Vendor (CNA)
Linux Linux5f0764cb1c81a9712bce605d38efe6d844a70b29Vendor (CNA)
Linux Linux6.12.113Vendor (CNA)
Linux Linux6.18.56Vendor (CNA)
Linux Linux6.2Vendor (CNA)
Linux Linux6.20Vendor (CNA)
Linux Linux6.6.160Vendor (CNA)
Linux Linuxaa480f05aed7a9eee87d4a6fc90647fe9679c670Vendor (CNA)
Linux Linuxcabacdf98e09eb74599c4d97d7bd7fd659598fb7Vendor (CNA)
Linux Linuxfdbd83c2d929ec968b37d2f75149a79440e328ffVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.159.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.12.113-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.113-1~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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 7, 2026+19 d
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. Exploit maturity— → none
  2. Fix✗ → ✓

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References

Show all references (4 more)

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

All records