GHSA-6237-rh4h-82p6 · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix...
In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix refcount leak on table dump There is a reference count leak in ctnetlink_dump_table(): if (res < 0) { nf_conntrack_get(&ct->ct_general); // HERE cb->args[1] = (unsigned long)ct; ... While its very unlikely, its possible that ct == last. If this happens, then the refcount of ct was already incremented. This 2nd increment is never undone. This prevents the conntrack object from being released, which in turn keeps prevents cnet->count from dropping back to 0. This will then block the netns dismantle (or conntrack rmmod) as nf_conntrack_cleanup_net_list() will wait forever. This can be reproduced by running conntrack_resize.sh selftest in a loop. It takes ~20 minutes for me on a preemptible kernel on average before I see a runaway kworker spinning in nf_conntrack_cleanup_net_list. One fix would to change this to: if (res < 0) { if (ct != last) nf_conntrack_get(&ct->ct_general); But this reference counting isn't needed in the first place. We can just store a cookie value instead. A followup patch will do the same for ctnetlink_exp_dump_table, it looks to me as if this has the same problem and like ctnetlink_dump_table, we only need a 'skip hint', not the actual object so we can apply the same cookie strategy there as well.
Conclusion & alert: CVE-2025-38721 is rated Low Risk (23.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.15%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.02% | 0.15% | +0.13% |
| 2 | 2026-01-10 | 0.06% | 0.02% | -0.04% |
| 3 | 2026-01-04 | — | 0.06% | — |
Full EPSS history (4 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 5.5 | 3.1 | MEDIUM |
|
1.8 | 3.6 | [email protected] |
GHSA-6237-rh4h-82p6 · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix...
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
not yet assigned | CVE-2025-38721 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. | https://security-tracker.debian.org/tracker/CVE-2025-38721 |
redhat
|
low | — | https://access.redhat.com/security/cve/CVE-2025-38721 |
suse
|
medium | CVE-2025-38721 severity moderate: SUSE including 456 source package names (2.1.3-6.80:kernel-default-base-6.4.0-35.1.21.12, 2.1.3-7.57:kernel-default-6.4.0-35.1, …), 879 product×package rows across 178 product lines (Container suse/sl-micro/6.0/base-os-container, Container suse/sl-micro/6.0/kvm-os-container, … (178 product lines)): Fixed 627, Known Affected 231, First Fixed 21. | https://www.suse.com/security/cve/CVE-2025-38721/ |
ubuntu
|
medium | CVE-2025-38721 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, ignored 180, released 150, needed 47, not-affected 17, needs-triage 2, pending 1. | https://ubuntu.com/security/CVE-2025-38721 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| linux | linux_kernel | >= 2.6.19, < 5.4.297 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | >= 5.5, < 5.10.241 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | >= 5.11, < 5.15.190 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | >= 5.16, < 6.1.149 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | >= 6.2, < 6.6.103 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | >= 6.7, < 6.12.43 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | >= 6.13, < 6.15.11 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | >= 6.16, < 6.16.2 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | 2.6.18 | cpe:2.3:o:linux:linux_kernel:2.6.18:-:*:*:*:*:*:* |
| linux | linux_kernel | 2.6.18 | cpe:2.3:o:linux:linux_kernel:2.6.18:rc5:*:*:*:*:*:* |
| linux | linux_kernel | 2.6.18 | cpe:2.3:o:linux:linux_kernel:2.6.18:rc6:*:*:*:*:*:* |
| linux | linux_kernel | 2.6.18 | cpe:2.3:o:linux:linux_kernel:2.6.18:rc7:*:*:*:*:*:* |
| linux | linux_kernel | 6.17 | cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* |
| debian | debian_linux | 11.0 | cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* |