CVE-2026-98438
In the Linux kernel, the following vulnerability has been resolved: mptcp: options: fix uninit-value in mptcp_write_data_fin When sending a DATA_FIN without data, and because the DATA_FIN occupies 1 octet of the connection-level sequence space [1], it is then required to add a DSS mapping with specific values. If the checksum has been negotiated, it also needs to be computed, and included in the outgoing packet, and thus the initial csum data needs to be reset to 0 as well. This is no longer the case since commit cfcceb7a39fc ("tcp: shrink per-packet memset in __tcp_transmit_skb()"), because the whole ext_copy structure is no longer zeroed by default. This seems to be the only case where use_map is changed and set afterwards, so initialising the csum field only in this case, along with other fields for this specific case.
Affected versions
Linux kernel versions
7.1
and later are affected. Fixed in
7.2.7,
7.3
and their respective stable series.
References
2 totalFrequently asked questions
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What is CVE-2026-98438?
CVE-2026-98438 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 7.1 onward and has been patched in 7.2.7 and 7.3. CVE-2026-98438 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-98438?
Yes. CVE-2026-98438 has been patched. Fixed versions include 7.2.7 and 7.3. If you are running Linux kernel 7.1 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-98438 actively exploited?
No. CVE-2026-98438 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.