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Response snapshot Oct 26, 2026, 21:56 UTC

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VulnerabilityCVE-2026-98555

Linux kernel: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure

In the Linux kernel, the following vulnerability has been resolved: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init() fails, kfree_skb(skb) is called instead of kfree_skb(nskb).

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.3% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-98555 (opens a new tab)

What happened

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

llc: fix skb UAF and leaks on llc_mac_hdr_init() failure

In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init() fails, kfree_skb(skb) is called instead of kfree_skb(nskb). This leaks the newly allocated nskb, reads from the freed skb via LLC_I_GET_NR(pdu), and double-frees skb when llc_conn_state_process() drops its reference.

In llc_sap_action_send_xid_r() and llc_sap_action_send_test_r(), nskb is leaked if llc_mac_hdr_init() returns an error.

Continue reading

Free nskb in all three error paths.

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.3%

Scored Percentile 23.6%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-98555 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-98555, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 24). Linux kernel: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure (CVE-2026-98555). https://kevwire.com/record/CVE-2026-98555

MLA

"Linux kernel: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure (CVE-2026-98555)." KEVWire, 24 Oct. 2026, kevwire.com/record/CVE-2026-98555.

Chicago

KEVWire. "Linux kernel: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure (CVE-2026-98555)." Last modified October 24, 2026. https://kevwire.com/record/CVE-2026-98555.

Evidence summary (plain text)

Linux kernel: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure (Oct 18, 2026).
In the Linux kernel, the following vulnerability has been resolved:

llc: fix skb UAF and leaks on llc_mac_hdr_init() failure

In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init()
fails, kfree_skb(skb) is called instead of kfree_skb(nskb). This leaks
the newly allocated nskb, reads from the freed skb via LLC_I_GET_NR(pdu),
and double-frees skb when llc_conn_state_process() drops its reference.

In llc_sap_action_send_xid_r() and llc_sap_action_send_test_r(), nskb is
leaked if llc_mac_hdr_init() returns an error.

Free nskb in all three error paths.
CVSS 7.5 (version 3.1; evidence as of Oct 24, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-98555).
EPSS 0.3% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-98555&date=2026-10-26).
Sources:
NVD CVE-2026-98555: https://nvd.nist.gov/vuln/detail/CVE-2026-98555
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=4500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-98555&date=2026-10-26
Record ID: CVE-2026-98555.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

Record detail