7.8

CVE-2025-21884: net: better track kernel sockets lifetime

Modified
AliasesUBUNTU-CVE-2025-21884DEBIAN-CVE-2025-21884
Published 27-03-2025Last modified 15-10-2026

Vulnerability summary

CVE-2025-21884 is a high (CVSS 7.8) vulnerability in linux. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 12.2% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.22%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 26 · Related 26
SUSE-SU-2025:01614-1SUSE-SU-2025:01707-1SUSE-SU-2025:01919-1SUSE-SU-2025:01951-1SUSE-SU-2025:01964-1SUSE-SU-2025:01967-1

Timeline

  1. 27-03-2025
    PublishedVulnerability first disclosed.
  2. 15-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: net: better track kernel sockets lifetime While kernel sockets are dismantled during pernet_operations->exit(), their freeing can be delayed by any tx packets still held in qdisc or device queues, due to skb_set_owner_w() prior calls. This then trigger the following warning from ref_tracker_dir_exit() [1] To fix this, make sure that kernel sockets own a reference on net->passive. Add sk_net_refcnt_upgrade() helper, used whenever a kernel socket is converted to a refcounted one. [1] [ 136.263918][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [ 136.263918][ T35] sk_alloc+0x2b3/0x370 [ 136.263918][ T35] inet6_create+0x6ce/0x10f0 [ 136.263918][ T35] __sock_create+0x4c0/0xa30 [ 136.263918][ T35] inet_ctl_sock_create+0xc2/0x250 [ 136.263918][ T35] igmp6_net_init+0x39/0x390 [ 136.263918][ T35] ops_init+0x31e/0x590 [ 136.263918][ T35] setup_net+0x287/0x9e0 [ 136.263918][ T35] copy_net_ns+0x33f/0x570 [ 136.263918][ T35] create_new_namespaces+0x425/0x7b0 [ 136.263918][ T35] unshare_nsproxy_namespaces+0x124/0x180 [ 136.263918][ T35] ksys_unshare+0x57d/0xa70 [ 136.263918][ T35] __x64_sys_unshare+0x38/0x40 [ 136.263918][ T35] do_syscall_64+0xf3/0x230 [ 136.263918][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 136.263918][ T35] [ 136.343488][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [ 136.343488][ T35] sk_alloc+0x2b3/0x370 [ 136.343488][ T35] inet6_create+0x6ce/0x10f0 [ 136.343488][ T35] __sock_create+0x4c0/0xa30 [ 136.343488][ T35] inet_ctl_sock_create+0xc2/0x250 [ 136.343488][ T35] ndisc_net_init+0xa7/0x2b0 [ 136.343488][ T35] ops_init+0x31e/0x590 [ 136.343488][ T35] setup_net+0x287/0x9e0 [ 136.343488][ T35] copy_net_ns+0x33f/0x570 [ 136.343488][ T35] create_new_namespaces+0x425/0x7b0 [ 136.343488][ T35] unshare_nsproxy_namespaces+0x124/0x180 [ 136.343488][ T35] ksys_unshare+0x57d/0xa70 [ 136.343488][ T35] __x64_sys_unshare+0x38/0x40 [ 136.343488][ T35] do_syscall_64+0xf3/0x230 [ 136.343488][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.22%

Chance of exploitation in the next 30 days

Percentile

12%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.21% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu112 products
  • linux< 6.8.0-100.100
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 6.8.0-1046.49
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 0cafd77dcd032d1687efaba5598cf07bce85997f, < 2668e038800b946d269f96ec1b258c01930a242c | ≥ 0cafd77dcd032d1687efaba5598cf07bce85997f, < 4ceb0bd4ffd009821b585ce6a8033b12b59fb5fb | ≥ 0cafd77dcd032d1687efaba5598cf07bce85997f, < c31a732fac46b00b95b78fcc9c37cb48dd6f2e0c | ≥ 0cafd77dcd032d1687efaba5598cf07bce85997f, < 5c70eb5c593d64d93b178905da215a9fd288a4b5 | 6.2
  • linux_kernel≥ 6.2, < 6.6.103 | ≥ 6.7, < 6.12.43 | ≥ 6.13, < 6.13.6 | 6.14:rc1 | 6.14:rc2 | 6.14:rc3 | 6.14:rc4
Debian1 product
  • linux< 6.12.43-1 | < 6.16.3-1

3 vendors · 115 products

References

25 links
Show all 25 references