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CVE-2026-98955

flow_dissector: avoid u16 truncation of skb->len when computing thoff

Products / packages Linux

Published

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Severity and exploitation

Not in CISA KEVNo CVSS score

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 21:15:32 UTC

Severity

unknown

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

In the Linux kernel, the following vulnerability has been resolved:

Source excerpt · Linux

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

Linux · Linux

Linux

14 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

d0c081b49137cd3200f2023c0875723be66e7ce5 → before 3f6000fdf8a57b9786669869af8a3e050b541bf3

git versions

d0c081b49137cd3200f2023c0875723be66e7ce5 → before 2c2f82b696c5e877f60ea77b7784e906a5e63014

git versions

d0c081b49137cd3200f2023c0875723be66e7ce5 → before d44e66f5dd99319a32e378b610af7fcf78da985a

git versions

d0c081b49137cd3200f2023c0875723be66e7ce5 → before d9e08836d06c84abb18470c94b12b131eaccdc7d

git versions

d0c081b49137cd3200f2023c0875723be66e7ce5 → before 50d0cd575cab763f833d6ac6eb6550b23a0b3dae

git versions

d0c081b49137cd3200f2023c0875723be66e7ce5 → before 9993e6a0ac1b5b3101ffba702cacb9f42b9909d8

git versions

d0c081b49137cd3200f2023c0875723be66e7ce5 → before 52efce4755a4b8b82039caa773645ffc80b25362

git versions

d0c081b49137cd3200f2023c0875723be66e7ce5 → before 99bda1ecbd56905f8bd934b9cdccd3bd251192b1

git versions

d35cd5e279881ec36ff8cd82a2d9caebc0cce3fc

git versions

eecfa2eeefe3caef4c8d6b2284f6066c76ab26a1

git versions

80f327285cab6ab8e10c3ea03278add5dd99fb02

git versions

4.4.114 → before 4.5

semver versions

4.9.79 → before 4.10

semver versions

4.14.16 → before 4.15

semver versions

unaffected

unknown

Other versions: unaffected

Linux · Linux

Linux

10 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

4.15

unaffected

0 → before 4.15

semver versions

5.10.273 → through 5.10.*

semver versions

5.15.224 → through 5.15.*

semver versions

6.1.191 → through 6.1.*

semver versions

6.6.160 → through 6.6.*

semver versions

6.12.113 → through 6.12.*

semver versions

6.18.57 → through 6.18.*

semver versions

7.2.11 → through 7.2.*

semver versions

7.3 → through *

original_commit_for_fix versions

unknown

Other versions: affected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

In the Linux kernel, the following vulnerability has been resolved:

flow_dissector: avoid u16 truncation of skb->len when computing thoff

__skb_flow_dissect() computes key_control->thoff using:

key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen);

min_t(u16, ...) casts both arguments to u16 before comparing them. Whenever skb->len (or hlen) modulo 65536 is smaller than nhoff, the truncated length wins and thoff is set to a bogus small value, even when the dissection succeeded. For example, an IPv4/TCP frame with skb->len == 65540 and nhoff == 34 gets thoff == 4, so callers such as skb_probe_transport_header() point the transport header inside the Ethernet header.

Such skbs are not exotic:

  • At the time of commit d0c081b49137 ("flow_dissector: properly cap thoff field"), AF_PACKET with PACKET_VNET_HDR could already build GSO skbs larger than 64KB (MTU checks are skipped for GSO, and alloc_skb_with_frags() accepted up to MAX_SKB_FRAGS (17) order-0 pages on top of the linear part).
  • BIG TCP now makes skbs larger than 64KB common.
  • The following patch makes tun_get_user() dissect IFF_TAP frames before eth_type_trans() pulls the Ethernet header, so a GSO frame carrying a 65522..65535 byte L3 packet will be dissected with skb->len in [65536, 65549].

Compare as u32 instead. If the resulting offset cannot be represented in the u16 key_control->thoff, cap it to U16_MAX and report the dissection as failed rather than silently returning a wrong transport offset. thoff is still set on failure, as some callers (such as eth_get_headlen()) use it regardless of the return value.

References

8 sources
git.kernel.org/stable/c/3f6000fdf8a57b9786669869af8a3e050b541bf3
Source referenceLinux
git.kernel.org/stable/c/2c2f82b696c5e877f60ea77b7784e906a5e63014
Source referenceLinux
git.kernel.org/stable/c/d44e66f5dd99319a32e378b610af7fcf78da985a
Source referenceLinux
git.kernel.org/stable/c/d9e08836d06c84abb18470c94b12b131eaccdc7d
Source referenceLinux
git.kernel.org/stable/c/50d0cd575cab763f833d6ac6eb6550b23a0b3dae
Source referenceLinux
git.kernel.org/stable/c/9993e6a0ac1b5b3101ffba702cacb9f42b9909d8
Source referenceLinux
View 2 more references
git.kernel.org/stable/c/52efce4755a4b8b82039caa773645ffc80b25362
Source referenceLinux
git.kernel.org/stable/c/99bda1ecbd56905f8bd934b9cdccd3bd251192b1
Source referenceLinux

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification · not supplied
Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-98955

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

Linux · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 5.10.273

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 5.15.224

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 6.1.191

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 6.6.160

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 6.12.113

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 6.18.57

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 7.2.11

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.15

Before: 7.3

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.4.114

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.9.79

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.14.16

Applicability preview
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            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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Contributing organizations · 1
Linux

Assigning organization

2026-10-30

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.