# CVE-2026-97602: inet: frags: invalidate queues before flushing them

> A race condition in Linux kernel IPv6 fragment reassembly allows local attackers to trigger heap corruption and escalate privileges via unprivileged network namespaces.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104538, BELL-CVE-2026-97602, DEBIAN-CVE-2026-97602, GHSA-82gw-3rjg-qh2p, UBUNTU-CVE-2026-97602

## What is CVE-2026-97602?

CVE-2026-97602 is a high-severity use after free vulnerability in Linux, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

inet: frags: invalidate queues before flushing them

fqdir_pre_exit() flushes the skbs from incomplete queues without
changing their completion state. A fragment which found a queue before
high_thresh was cleared can then acquire the queue lock and reuse stale
reassembly metadata. A queue concurrently killed after fqdir->dead is
set can instead become INET_FRAG_COMPLETE|INET_FRAG_HASH_DEAD while
still holding its old skbs; skipping it because it is complete leaves
those references behind until asynchronous fqdir teardown.

For IPv6, stale metadata can make ip6_frag_reasm() use the old
nhoffset with a new skb and access memory out of bounds. The resulting
heap corruption can be leveraged for local privilege escalation when
unprivileged network namespaces are available. Unflushed fragments can
also keep conntrack references alive after the conntrack per-net
cleanup point.

Kill each incomplete queue, then flush every queue still owned by the
dying rhashtable. HASH_DEAD identifies that ownership, while complete
queues without it are already owned by another destroy path and must be
left alone. Releasing a timer reference removed by inet_frag_kill() is
deferred to inet_frag_putn(), after the queue lock is dropped.

KASAN report:

  BUG: KASAN: slab-out-of-bounds in ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))
  Write of size 1 at addr ff110001039c6e00 by task poc/771
  Call Trace:
  ? ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))
  ipv6_frag_rcv (net/ipv6/reassembly.c:289 (discriminator 2) net/ipv6/reassembly.c:229 (discriminator 2) net/ipv6/reassembly.c:391 (discriminator 2))
  ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479 (discriminator 5))
  ip6_input_finish (net/ipv6/ip6_input.c:534)
  ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3))
  packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142)
  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)
  The buggy address belongs to the object at ff110001039c6b40
  which belongs to the cache skbuff_small_head of size 704
  The buggy address is located 0 bytes to the right of
  allocated 704-byte region [ff110001039c6b40, ff110001039c6e00)

  BUG: KASAN: slab-out-of-bounds in ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))
  Read of size 1 at addr ff110001039c6e08 by task poc/771
  Call Trace:
  ? ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))
  ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:423 (discriminator 1))
  ip6_input_finish (net/ipv6/ip6_input.c:534)
  ipv6_rcv (include/net/dst.h:480 (discriminator 3) net/ipv6/ip6_input.c:119 (discriminator 3) net/ipv6/ip6_input.c:109 (discriminator 3) include/linux/netfilter.h:325 (discriminator 3) include/linux/netfilter.h:319 (discriminator 3) net/ipv6/ip6_input.c:351 (discriminator 3))
  packet_sendmsg (net/packet/af_packet.c:3110 net/packet/af_packet.c:3142)
  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)
  packet_sendmsg (net/packet/af_packet.c:2959 net/packet/af_packet.c:3053 net/packet/af_packet.c:3142)
  __x64_sys_sendmmsg (net/socket.c:2883 net/socket.c:2880 net/socket.c:2880)
  The buggy address belongs to the object at ff110001039c6b40
  which belongs to the cache skbuff_small_head of size 704
  The buggy address is located 8 bytes to the right of
  allocated 704-byte region [ff110001039c6b40, ff110001039c6e00)

## Which versions are affected by CVE-2026-97602?


## How do I fix CVE-2026-97602?

Apply the vendor's patch.

## Is CVE-2026-97602 being exploited?

There is no known exploitation of CVE-2026-97602 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97602 and fix it if it is affected.

What it is: CVE-2026-97602 is a high-severity use after free vulnerability in Linux, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-97602 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-97602/ (Markdown: https://insights.sbomify.com/CVE-2026-97602/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97602
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97602
- OSV: https://osv.dev/vulnerability/CVE-2026-97602

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97602/
Summaries are generated and may contain mistakes; the official description above is the record.