CVE-2026-74664: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: reallocate update replies for mismatched IDs ovs_flow_cmd_new() preallocates the optional reply skb before it takes ovs_mutex and before it knows which existing flow will be updated. That is normally fine because the skb is sized from the request flow identifier. That identifier also becomes the inserted flow's identifier. For updates, however, a request with a UFID may miss the UFID lookup and then fall back to the flow key lookup. That lookup can legitimately find an existing key-identified flow. UFIDs are optional and the flow key is the primary identifier. For echoed replies, ovs_flow_cmd_fill_info() writes the matched flow's identifier, not the request identifier used for the preallocation. A short request UFID can therefore leave too little room for the key identifier. The fill can then fail with -EMSGSIZE and hit the BUG_ON(error < 0) in the update path. Once the update target has been resolved, reallocate the reply skb if the matched flow needs a larger reply than the request identifier allowed. Do this before replacing the actions so the request can still fail cleanly if the rare extra allocation fails.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 74ed7ab9264c54471c7f057409d352052820d750, < bd8ca84d48cd9a4f6fc63df26512c55e1d339927; >= 74ed7ab9264c54471c7f057409d352052820d750, < 00f987f066e802793a37dd2167459e67cf2cf2ec; >= 74ed7ab9264c54471c7f057409d352052820d750, < 696a0b9435fce9cf4f1e9ba7f6afa6bee96c97fc; >= 74ed7ab9264c54471c7f057409d352052820d750, < 87d0c0040b5d4b61de51ae39132c4c46709f2f77; >= 74ed7ab9264c54471c7f057409d352052820d750, < 69f40ccf85074981340847d650a9cbf9adabfbbe; >= 74ed7ab9264c54471c7f057409d352052820d750, < 23716dd9d8d46a5908536b73dc085e62f2b5c237; >= 74ed7ab9264c54471c7f057409d352052820d750, < 20751193d83be2e9735d4faee71375691c09cd13; >= 74ed7ab9264c54471c7f057409d352052820d750, < 5d1c224dd914579524a183a514c12b95095d12ce
Linux	Linux	4.0

References

Timeline

Published: Aug 22, 2026
Last Modified: Aug 22, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-74664?

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: reallocate update replies for mismatched IDs ovs_flow_cmd_new() preallocates the optional reply skb before it takes ovs_mutex and before it knows which existing flow will be updated. That is normally fine because the skb is sized from the request flow identifier. That identifier also becomes the inserted flow's identifier. For updates, however, a request with a UFID may miss the UFID lookup and then fall back to the flow key lookup. That lookup can legitimately find an existing key-identified flow. UFIDs are optional and the flow key is the primary identifier. For echoed replies, ovs_flow_cmd_fill_info() writes the matched flow's identifier, not the request identifier used for the preallocation. A short request UFID can therefore leave too little room for the key identifier. The fill can then fail with -EMSGSIZE and hit the BUG_ON(error < 0) in the update path. Once the update target has been resolved, reallocate the reply skb if the matched flow needs a larger reply than the request identifier allowed. Do this before replacing the actions so the request can still fail cleanly if the rare extra allocation fails.

How severe is CVE-2026-74664?

Severity scoring for CVE-2026-74664 is pending analysis.

How do I fix CVE-2026-74664?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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