CVE-2021-47232 (GCVE-0-2021-47232)
Vulnerability from cvelistv5 – Published: 2024-05-21 14:19 – Updated: 2026-08-05 08:46
VLAI
EPSS
VEX
Title
can: j1939: fix Use-after-Free, hold skb ref while in use
Summary
In the Linux kernel, the following vulnerability has been resolved:
can: j1939: fix Use-after-Free, hold skb ref while in use
This patch fixes a Use-after-Free found by the syzbot.
The problem is that a skb is taken from the per-session skb queue,
without incrementing the ref count. This leads to a Use-after-Free if
the skb is taken concurrently from the session queue due to a CTS.
Severity
9.8 (Critical)
8.4 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-05-28 19:03 UTC
CWE
- CWE-416 - Use After Free
Assigner
References
Impacted products
12 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
9d71dd0c70099914fcd063135da3c580865e924c , < 22cba878abf646cd3a02ee7c8c2cef7afe66a256
(git)
Affected: 9d71dd0c70099914fcd063135da3c580865e924c , < 509ab6bfdd0c76daebbad0f0af07da712116de22 (git) Affected: 9d71dd0c70099914fcd063135da3c580865e924c , < 1071065eeb33d32b7d98c2ce7591881ae7381705 (git) Affected: 9d71dd0c70099914fcd063135da3c580865e924c , < 2030043e616cab40f510299f09b636285e0a3678 (git) |
guessed | |
| Linux | Linux |
Affected:
5.4
Unaffected: 0 , < 5.4 (semver) Unaffected: 5.4.128 , ≤ 5.4.* (semver) Unaffected: 5.10.46 , ≤ 5.10.* (semver) Unaffected: 5.12.13 , ≤ 5.12.* (semver) Unaffected: 5.13 , ≤ * (original_commit_for_fix) |
guessed | |
| linux | linux_kernel |
Affected:
9d71dd0c7009 , < 22cba878abf6
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Affected:
9d71dd0c7009 , < 509ab6bfdd0c
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Affected:
9d71dd0c7009 , < 1071065eeb33
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Affected:
9d71dd0c7009 , < 2030043e616c
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Unaffected:
5.4.128 , < 5.5
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Unaffected:
5.10.46 , < 5.11
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Unaffected:
5.12.13 , < 5.13
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Unaffected:
5.13
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Unaffected:
0 , < 5.4
(custom)
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* |
||
| linux | linux_kernel |
Affected:
5.4
cpe:2.3:o:linux:linux_kernel:5.4:-:*:*:*:*:*:* |
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"value": "AV:N - The UAF is reached via can_rcv \u2192 j1939_can_recv \u2192 j1939_tp_recv when processing peer TP.CM_CTS/DAT frames; an unauthenticated J1939/CAN peer drives the race, consistent with other packet-triggered j1939 scores (e.g. CVE-2024-56645).\nAC:L - The attacker controls CTS injection timing against an active TP session and can retry indefinitely; when both sides of the race are attacker-driven (local sockets/vcan or crafted bus traffic), success does not depend on conditions outside attacker influence.\nPR:N - J1939 receive processing has no authentication; a bus peer needs no credentials on the target, and the same path is also reachable from an unprivileged AF_CAN/CAN_J1939 socket with no capability checks on create/bind/send.\nUI:N - Frames are handled in softirq with no victim action required beyond a bound J1939 socket, which is the normal steady state on systems using this stack.\nS:U - The corrupted sk_buff and resulting privilege impact remain within the kernel\u0027s security authority; this is not a VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:H - Use-after-free of the session skb enables heap grooming and arbitrary read of freed object contents (including via continued use of the dangling skb pointer in TX/RX data paths).\nI:H - The same UAF yields a reclaimable freed sk_buff that can be sprayed for arbitrary write and control-flow hijacking primitives in the kernel heap.\nA:H - Dereferencing the freed skb causes kernel oops/panic, and an unauthenticated peer can trigger the race repeatedly to deny service."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T08:46:51.007Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/22cba878abf646cd3a02ee7c8c2cef7afe66a256"
},
{
"url": "https://git.kernel.org/stable/c/509ab6bfdd0c76daebbad0f0af07da712116de22"
},
{
"url": "https://git.kernel.org/stable/c/1071065eeb33d32b7d98c2ce7591881ae7381705"
},
{
"url": "https://git.kernel.org/stable/c/2030043e616cab40f510299f09b636285e0a3678"
}
],
"title": "can: j1939: fix Use-after-Free, hold skb ref while in use",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2021-47232",
"datePublished": "2024-05-21T14:19:35.084Z",
"dateReserved": "2024-04-10T18:59:19.530Z",
"dateUpdated": "2026-08-05T08:46:51.007Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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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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