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Public proof of conceptFix available

CVE-2026-68121

A public proof of concept exists; no exploitation attested.

  • Published2026-08-10
  • WeaknessCWE-416

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

In the Linux kernel, the following vulnerability has been resolved: pppoe: reload header pointer after dev_hard_header() pppoe_sendmsg() saves a pointer to the PPPoE header before calling dev_hard_header(). Device header callbacks are allowed to reallocate the skb head, invalidating pointers into it. This can happen when a send is blocked in copy_from_user() while the first non-Ethernet port is added to an empty team device. The team's delegated GRE header callback then expands the skb head. PPPoE subsequently writes six bytes through the stale pointer into the freed head. Reload the PPPoE header through the skb's network-header offset after device header creation. pskb_expand_head() updates that offset when it relocates the head.

Timeline

dates in UTC
  1. 2026-08-1013:19CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-68121?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-68121?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • kernelAlmaLinux:10all versions · fixed in 6.12.0-211.60.1.el10_2and 74 other packages
  • kernelAlmaLinux:9all versions · fixed in 5.14.0-687.52.1.el9_8and 73 other packages
  • kernelAlmaLinux:8all versions · fixed in 4.18.0-553.168.1.el8_10and 24 other packages
  • kernel-rtAlmaLinux:8all versions · fixed in 4.18.0-553.168.1.rt7.509.el8_10and 9 other packages

Vendor advisories

  • CVE-2026-68121 Red Hat Product Security2,360 products fixed · 23 known affected

    kernel: pppoe: reload header pointer after dev_hard_header()

    kernel-rt as a component of Red Hat Enterprise Linux 9 · kernel-rt-core as a component of Red Hat Enterprise Linux 9 · kernel-rt-debug as a component of Red Hat Enterprise Linux 9 · +20 more

  • RHSA-2026:82782 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.14.76 bug fix and security update

  • RHSA-2026:82811 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.15.70 bug fix and security update

  • RHSA-2026:83479 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.19.52 bug fix and security update

  • RHSA-2026:83540 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.22.19 bug fix and security update

  • RHSA-2026:74377 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.20.41 bug fix and security update

17 more advisories

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2026:82782 · 4 productsFor OpenShift Container Platform 4.14 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  2. Vendor fix Red Hat Product Security RHSA-2026:82811 · 4 productsFor OpenShift Container Platform 4.15 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  3. Vendor fix Red Hat Product Security RHSA-2026:83479 · 4 productsFor OpenShift Container Platform 4.19 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  4. Vendor fix Red Hat Product Security RHSA-2026:83540 · 4 productsFor OpenShift Container Platform 4.22 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  5. Vendor fix Red Hat Product Security RHSA-2026:74377 · 4 productsFor OpenShift Container Platform 4.20 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  6. Vendor fix Red Hat Product Security RHSA-2026:74379 · 4 productsFor OpenShift Container Platform 4.21 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…

Detection

read 2026-10-23 19:25 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
3 repositories, unverifiedsuominen/pppoeject0xBlackash/CVE-2026-68121HORKimhab/CVE-2026-68121
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2026-08-10
Last Modified
2026-10-19
NVD status
Received

Frequently asked questions

What is CVE-2026-68121?

In the Linux kernel, the following vulnerability has been resolved: pppoe: reload header pointer after dev_hard_header() pppoe_sendmsg() saves a pointer to the PPPoE header before calling dev_hard_header(). Device header callbacks are allowed to reallocate the skb head, invalidating pointers into it. This can happen when a send is blocked in copy_from_user() while the first non-Ethernet port is added to an empty team device. The team's delegated GRE header callback then expands the skb head. PPPoE subsequently writes six bytes through the stale pointer into the freed head. Reload the PPPoE header through the skb's network-header offset after device header creation. pskb_expand_head() updates that offset when it relocates the head.

Is CVE-2026-68121 actively exploited?

Active exploitation of CVE-2026-68121 has not been confirmed. Its EPSS score was 0.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-68121?

CVE-2026-68121 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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