CVE-2026-31504 (GCVE-0-2026-31504)
Vulnerability from cvelistv5 – Published: 2026-04-22 13:54 – Updated: 2026-09-08 08:47
VLAI
EPSS
VEX
Title
net: fix fanout UAF in packet_release() via NETDEV_UP race
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: fix fanout UAF in packet_release() via NETDEV_UP race
`packet_release()` has a race window where `NETDEV_UP` can re-register a
socket into a fanout group's `arr[]` array. The re-registration is not
cleaned up by `fanout_release()`, leaving a dangling pointer in the fanout
array.
`packet_release()` does NOT zero `po->num` in its `bind_lock` section.
After releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex`
still matches the bound device. A concurrent `packet_notifier(NETDEV_UP)`
that already found the socket in `sklist` can re-register the hook.
For fanout sockets, this re-registration calls `__fanout_link(sk, po)`
which adds the socket back into `f->arr[]` and increments `f->num_members`,
but does NOT increment `f->sk_ref`.
The fix sets `po->num` to zero in `packet_release` while `bind_lock` is
held to prevent NETDEV_UP from linking, preventing the race window.
This bug was found following an additional audit with Claude Code based
on CVE-2025-38617.
Severity
7.8 (High)
Assigner
References
10 references
Impacted products
8 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < ee642b1962caa9aa231c01abbd58bc453ae6b66e
(git)
Affected: ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < 42cfd7898eeed290c9fb73f732af1f7d6b0a703e (git) Affected: ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < 1b4c03f8892d955385c202009af7485364731bb9 (git) Affected: ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < 654386baef228c2992dbf604c819e4c7c35fc71b (git) Affected: ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < 75fe6db23705a1d55160081f7b37db9665b1880b (git) Affected: ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6 (git) Affected: ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < ceccbfc6de720ad633519a226715989cfb065af1 (git) Affected: ce06b03e60fc19c680d1bf873e779bf11c2fc518 , < 42156f93d123436f2a27c468f18c966b7e5db796 (git) |
guessed | |
| Linux | Linux |
Affected:
3.1
Unaffected: 0 , < 3.1 (semver) Unaffected: 5.10.253 , ≤ 5.10.* (semver) Unaffected: 5.15.203 , ≤ 5.15.* (semver) Unaffected: 6.1.168 , ≤ 6.1.* (semver) Unaffected: 6.6.131 , ≤ 6.6.* (semver) Unaffected: 6.12.80 , ≤ 6.12.* (semver) Unaffected: 6.18.21 , ≤ 6.18.* (semver) Unaffected: 6.19.11 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix) |
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed | |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed |
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}
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}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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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.
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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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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