CVE-2026-98491 (CVSS 7.8)

Description

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry In a case where skb with an unconfirmed ct entry gets cloned, we may end up committing both but with different sets of extensions. The series of events: 1. The first clone wants to commit and runs the helpers wiring up the extension pointer into the expectation list. 2. Then it looses the confirmation keeping the entry unconfirmed. 3. Second clone now wants to commit labels and adds the new extension for that breaking the pointer in the expectation list causing UAF on the destruction path later. While this is possible to trigger, there should be no practical network pipeline where committing both clones without modifications into the same zone is needed. So, let's just reset the entry in case for some reason we got an skb with a shared one during commit. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry. The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing.

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CVSS v3.1 Score

7.8

HIGH

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

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.06%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/26b2bd70d22457556e2fa01cbf1192cb1a94d619 https://git.kernel.org/stable/c/37e3c878b183a115f9a114067f9ef3b408ad27fb https://git.kernel.org/stable/c/457e0df1b5711fbeb7ba1b6bfd826f5ef30e7e55 https://git.kernel.org/stable/c/55e5256adf3940e71802e2f749cacf81518726b0 https://git.kernel.org/stable/c/707c2dc77891a874f4e8c52c285a511079164ec8 https://git.kernel.org/stable/c/de41ee24f77b0fc45397db3e277cae2adbd43dfe https://git.kernel.org/stable/c/e0fa5ea434b7e8467ef3adc64e3858b1ca2a642d https://git.kernel.org/stable/c/e2829ae5459ddb5fce526b2e84697edf6c0c3cef

Frequently Asked Questions

What is CVE-2026-98491? +

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry In a case where skb with an unconfirmed ct entry gets cloned, we may end up committing both but with different sets of extensions. The series of events: 1. The first clone wants to commit and runs the helpers wiring up the extension pointer into the expectation list. 2. Then it looses the confirmation keeping the entry unconfirmed. 3. Second clone now wants to commit labels and adds the new extension for that breaking the pointer in the expectation list causing UAF on the destruction path later. While this is possible to trigger, there should be no practical network pipeline where committing both clones without modifications into the same zone is needed. So, let's just reset the entry in case for some reason we got an skb with a shared one during commit. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry. The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-98491? +

CVE-2026-98491 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0017, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-98491? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-98491