CVE-2026-53070 (GCVE-0-2026-53070)
Vulnerability from cvelistv5 – Published: 2026-06-24 16:30 – Updated: 2026-08-05 12:33
VLAI
EPSS
VEX
Title
sctp: disable BH before calling udp_tunnel_xmit_skb()
Summary
In the Linux kernel, the following vulnerability has been resolved:
sctp: disable BH before calling udp_tunnel_xmit_skb()
udp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with
BH disabled. After commit 6f1a9140ecda ("add xmit recursion limit to
tunnel xmit functions"), on the path:
udp(6)_tunnel_xmit_skb() -> ip(6)tunnel_xmit()
dev_xmit_recursion_inc()/dec() must stay balanced on the same CPU.
Without local_bh_disable(), the context may move between CPUs, which can
break the inc/dec pairing. This may lead to incorrect recursion level
detection and cause packets to be dropped in ip(6)_tunnel_xmit() or
__dev_queue_xmit().
Fix it by disabling BH around both IPv4 and IPv6 SCTP UDP xmit paths.
In my testing, after enabling the SCTP over UDP:
# ip net exec ha sysctl -w net.sctp.udp_port=9899
# ip net exec ha sysctl -w net.sctp.encap_port=9899
# ip net exec hb sysctl -w net.sctp.udp_port=9899
# ip net exec hb sysctl -w net.sctp.encap_port=9899
# ip net exec ha iperf3 -s
- without this patch:
# ip net exec hb iperf3 -c 192.168.0.1 --sctp
[ 5] 0.00-10.00 sec 37.2 MBytes 31.2 Mbits/sec sender
[ 5] 0.00-10.00 sec 37.1 MBytes 31.1 Mbits/sec receiver
- with this patch:
# ip net exec hb iperf3 -c 192.168.0.1 --sctp
[ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec sender
[ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec receiver
Severity
7.5 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
046c052b475e7119b6a30e3483e2888fc606a2f8 , < be3bfcb34bda04f6a350710db471d4133f950f2c
(git)
Affected: 046c052b475e7119b6a30e3483e2888fc606a2f8 , < 0de7db2eb27e82b983157016fa604b1ba664ae5f (git) Affected: 046c052b475e7119b6a30e3483e2888fc606a2f8 , < 790093245e35040c2adb15f48970020425aa3f47 (git) Affected: 046c052b475e7119b6a30e3483e2888fc606a2f8 , < 2cd7e6971fc2787408ceef17906ea152791448cf (git) |
guessed | |
| Linux | Linux |
Affected:
5.11
Unaffected: 0 , < 5.11 (semver) Unaffected: 6.12.95 , ≤ 6.12.* (semver) Unaffected: 6.18.37 , ≤ 6.18.* (semver) Unaffected: 7.0.10 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix) |
guessed |
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}
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}
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{
"url": "https://git.kernel.org/stable/c/2cd7e6971fc2787408ceef17906ea152791448cf"
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"datePublished": "2026-06-24T16:30:11.816Z",
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"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-53070.json",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: disable BH before calling udp_tunnel_xmit_skb()\n\nudp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with\nBH disabled. After commit 6f1a9140ecda (\"add xmit recursion limit to\ntunnel xmit functions\"), on the path:\n\n udp(6)_tunnel_xmit_skb() -\u003e ip(6)tunnel_xmit()\n\ndev_xmit_recursion_inc()/dec() must stay balanced on the same CPU.\n\nWithout local_bh_disable(), the context may move between CPUs, which can\nbreak the inc/dec pairing. This may lead to incorrect recursion level\ndetection and cause packets to be dropped in ip(6)_tunnel_xmit() or\n__dev_queue_xmit().\n\nFix it by disabling BH around both IPv4 and IPv6 SCTP UDP xmit paths.\n\nIn my testing, after enabling the SCTP over UDP:\n\n # ip net exec ha sysctl -w net.sctp.udp_port=9899\n # ip net exec ha sysctl -w net.sctp.encap_port=9899\n # ip net exec hb sysctl -w net.sctp.udp_port=9899\n # ip net exec hb sysctl -w net.sctp.encap_port=9899\n\n # ip net exec ha iperf3 -s\n\n- without this patch:\n\n # ip net exec hb iperf3 -c 192.168.0.1 --sctp\n [ 5] 0.00-10.00 sec 37.2 MBytes 31.2 Mbits/sec sender\n [ 5] 0.00-10.00 sec 37.1 MBytes 31.1 Mbits/sec receiver\n\n- with this patch:\n\n # ip net exec hb iperf3 -c 192.168.0.1 --sctp\n [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec sender\n [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec receiver"
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"id": "CVE-2026-53070",
"lastModified": "2026-07-21T17:39:27.027",
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"suse_vex": {
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"product_status:recommended": "250",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-53070",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-53070.json",
"version": "7"
}
}
}
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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
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