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EUVD-2026-344338

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-02 07:56

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

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{
  "assigner": "ENISA",
  "date_reserved": "2026-10-02T07:56:03.094534+00:00",
  "id": "EUVD-2026-344338"
}

CVE-2021-46936 (GCVE-0-2021-46936)

Vulnerability from cvelistv5 – Published: 2024-02-27 09:44 – Updated: 2026-08-05 08:45

Title

net: fix use-after-free in tw_timer_handler

Summary

In the Linux kernel, the following vulnerability has been resolved: net: fix use-after-free in tw_timer_handler A real world panic issue was found as follow in Linux 5.4. BUG: unable to handle page fault for address: ffffde49a863de28 PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0 RIP: 0010:tw_timer_handler+0x20/0x40 Call Trace: <IRQ> call_timer_fn+0x2b/0x120 run_timer_softirq+0x1ef/0x450 __do_softirq+0x10d/0x2b8 irq_exit+0xc7/0xd0 smp_apic_timer_interrupt+0x68/0x120 apic_timer_interrupt+0xf/0x20 This issue was also reported since 2017 in the thread [1], unfortunately, the issue was still can be reproduced after fixing DCCP. The ipv4_mib_exit_net is called before tcp_sk_exit_batch when a net namespace is destroyed since tcp_sk_ops is registered befrore ipv4_mib_ops, which means tcp_sk_ops is in the front of ipv4_mib_ops in the list of pernet_list. There will be a use-after-free on net->mib.net_statistics in tw_timer_handler after ipv4_mib_exit_net if there are some inflight time-wait timers. This bug is not introduced by commit f2bf415cfed7 ("mib: add net to NET_ADD_STATS_BH") since the net_statistics is a global variable instead of dynamic allocation and freeing. Actually, commit 61a7e26028b9 ("mib: put net statistics on struct net") introduces the bug since it put net statistics on struct net and free it when net namespace is destroyed. Moving init_ipv4_mibs() to the front of tcp_init() to fix this bug and replace pr_crit() with panic() since continuing is meaningless when init_ipv4_mibs() fails. [1] https://groups.google.com/g/syzkaller/c/p1tn-_Kc6l4/m/smuL_FMAAgAJ?pli=1

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-09-10 16:01 UTC

Assigner

Linux mitre root Scorecard

References

8 references

URL	Tags
https://git.kernel.org/stable/c/15579e1301f856ad9…
https://git.kernel.org/stable/c/e73164e89d1be5612…
https://git.kernel.org/stable/c/5c2fe20ad37ff5607…
https://git.kernel.org/stable/c/a8e1944b44f94f5c5…
https://git.kernel.org/stable/c/fe5838c22b986c119…
https://git.kernel.org/stable/c/2386e81a1d277f540…
https://git.kernel.org/stable/c/08eacbd141e2495d2…
https://git.kernel.org/stable/c/e22e45fc9e41bf9fc…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < 15579e1301f856ad9385d720c9267c11032a5022 (git) Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < e73164e89d1be561228a4534e1091369ee4ba41a (git) Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < 5c2fe20ad37ff56070ae0acb34152333976929b4 (git) Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < a8e1944b44f94f5c5f530e434c5eaee787254566 (git) Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < fe5838c22b986c1190f1dce9aa09bf6a491c1a69 (git) Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < 2386e81a1d277f540e1285565c9d41d531bb69d4 (git) Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < 08eacbd141e2495d2fcdde84358a06c4f95cbb13 (git) Affected: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 , < e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0 (git)
Linux	Linux	Affected: 2.6.27 Unaffected: 0 , < 2.6.27 (semver) Unaffected: 4.4.298 , ≤ 4.4.* (semver) Unaffected: 4.9.296 , ≤ 4.9.* (semver) Unaffected: 4.14.261 , ≤ 4.14.* (semver) Unaffected: 4.19.224 , ≤ 4.19.* (semver) Unaffected: 5.4.170 , ≤ 5.4.* (semver) Unaffected: 5.10.90 , ≤ 5.10.* (semver) Unaffected: 5.15.13 , ≤ 5.15.* (semver) Unaffected: 5.16 , ≤ * (original_commit_for_fix)

Show details on NVD website

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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EUVD-2026-344338

CVE-2021-46936 (GCVE-0-2021-46936)

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