A vulnerability in the Linux kernel SCTP over UDP transmission path was fixed by ensuring bottom halves (BH) are disabled before calling… (CVE-2026-53070)
A vulnerability in the Linux kernel SCTP over UDP transmission path was fixed by ensuring bottom halves (BH) are disabled before calling udp_tunnel_xmit_skb() and udp_tunnel6_xmit_skb(). Without disabling BH, recursion level detection can fail due to CPU context switching, causing packet drops and degraded SCTP over UDP performance.
AI Analysis
Technical Summary
The Linux kernel SCTP UDP transmit functions udp_tunnel_xmit_skb() and udp_tunnel6_xmit_skb() require BH to be disabled to maintain balanced dev_xmit_recursion_inc()/dec() calls on the same CPU. A recent commit introduced a recursion limit, but without local_bh_disable(), the context may move between CPUs, breaking this balance. This leads to incorrect recursion detection and packet drops in ip(6)_tunnel_xmit() or __dev_queue_xmit(). The vulnerability was resolved by disabling BH around both IPv4 and IPv6 SCTP UDP transmit paths, improving SCTP over UDP throughput significantly.
Potential Impact
The vulnerability causes packet drops in SCTP over UDP transmissions due to incorrect recursion level detection, resulting in significantly degraded network throughput and reliability for affected SCTP UDP traffic. There is no indication of confidentiality or integrity impact, but availability is affected due to packet loss.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to disable BH before calling udp_tunnel_xmit_skb() and udp_tunnel6_xmit_skb(), resolving the recursion detection issue and preventing packet drops. Users should apply the official kernel update containing this fix once available. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.
A vulnerability in the Linux kernel SCTP over UDP transmission path was fixed by ensuring bottom halves (BH) are disabled before calling… (CVE-2026-53070)
Description
A vulnerability in the Linux kernel SCTP over UDP transmission path was fixed by ensuring bottom halves (BH) are disabled before calling udp_tunnel_xmit_skb() and udp_tunnel6_xmit_skb(). Without disabling BH, recursion level detection can fail due to CPU context switching, causing packet drops and degraded SCTP over UDP performance.
CVSS v3.1
Score 7.5high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel SCTP UDP transmit functions udp_tunnel_xmit_skb() and udp_tunnel6_xmit_skb() require BH to be disabled to maintain balanced dev_xmit_recursion_inc()/dec() calls on the same CPU. A recent commit introduced a recursion limit, but without local_bh_disable(), the context may move between CPUs, breaking this balance. This leads to incorrect recursion detection and packet drops in ip(6)_tunnel_xmit() or __dev_queue_xmit(). The vulnerability was resolved by disabling BH around both IPv4 and IPv6 SCTP UDP transmit paths, improving SCTP over UDP throughput significantly.
Potential Impact
The vulnerability causes packet drops in SCTP over UDP transmissions due to incorrect recursion level detection, resulting in significantly degraded network throughput and reliability for affected SCTP UDP traffic. There is no indication of confidentiality or integrity impact, but availability is affected due to packet loss.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to disable BH before calling udp_tunnel_xmit_skb() and udp_tunnel6_xmit_skb(), resolving the recursion detection issue and preventing packet drops. Users should apply the official kernel update containing this fix once available. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-q4jf-gp35-367g
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-53070"]
- Ecosystems
- []
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6a498a7327e9c7971936ea22
Added to database: 07/04/2026, 22:34:27 UTC
Last enriched: 07/04/2026, 23:07:42 UTC
Last updated: 07/31/2026, 19:24:49 UTC
Views: 22
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