CVE-2026-98441net/sched: act_ct: avoid modifying shared unconfirmed ct entry
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: avoid modifying shared unconfirmed ct entry In a case where skb with an unconfirmed ct entry gets cloned, we may end up processing both again 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 or run NAT 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 we need to process both clones without modifications in the same zone. So, let's just reset the entry in case for some reason we got an skb with a shared one. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry. Unlike openvswitch module, act_ct allows for NAT without commit. Changing that would be a uAPI break. So, act_ct needs to reset on NAT regardless of the commit flag to avoid reallocation of the extension space. This, however, doesn't really change the picture for sensible networking cases as there should be no need to run the same packet twice (before and after the clone) through conntrack without packet header or zone changes and without commit. The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing.
- CVSS
- Not yet scored
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 18, 2026
- First seen by InfoSec Signals
- Oct 18, 2026
Affected products
Linux Linux linux:linux (from the name) | from a21b06e7319129994f339ed47f512bbe57b77f5b before 2b783c562c3238ff50c34fd7a72a735c9cc73d9a; from a21b06e7319129994f339ed47f512bbe57b77f5b before 4a04ed91575819fb1859311113e95700b709bec7; from a21b06e7319129994f339ed47f512bbe57b77f5b before b097d9d7a5b09c8ec5c4c1a08e35ac5a66b06b44; from a21b06e7319129994f339ed47f512bbe57b77f5b before f85009dfcd65e5969526b0db7a49b5413746e630 | CNA record |
References
- https://git.kernel.org/stable/c/2b783c562c3238ff50c34fd7a72a735c9cc73d9a
- https://git.kernel.org/stable/c/4a04ed91575819fb1859311113e95700b709bec7
- https://git.kernel.org/stable/c/b097d9d7a5b09c8ec5c4c1a08e35ac5a66b06b44
- https://git.kernel.org/stable/c/f85009dfcd65e5969526b0db7a49b5413746e630
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.