CVE-2026-99270
tcp: Fix potential UAF in reqsk_timer_handler().
What happened?
In the Linux kernel, the following vulnerability has been resolved:
tcp: Fix potential UAF in reqsk_timer_handler().
When TCP socket migration fails at inet_ehash_insert() in reqsk_timer_handler(), we jump to the no_ownership: label and free the new reqsk immediately with __reqsk_free().
Thus, we must stop the new reqsk's timer before jumping to the label, but the timer might be missed since the cited commit, resulting in UAF.
As we are in the original reqsk's timer context, we can safely call timer_delete_sync() for the new reqsk.
Let's pass false to __inet_csk_reqsk_queue_drop() to stop the new reqsk's timer.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| LinuxLinux | affected: 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af to < 97c8a3c1f73d828de43a5a88e8a9a143efb2b661; affected: d3a1196bfc462943694623412d8e03aaf172bdc1; affected: 4.1.11 to < 4.2 | See vendor advisory |
| LinuxLinux | affected: 4.2; unaffected: 0 to < 4.2; unaffected: 7.1 to ≤ * | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.