# CVE-2022-48956: ipv6: avoid use-after-free in ip6_fragment()

> A use-after-free vulnerability in the Linux kernel IPv6 fragmentation code allows attackers to cause a denial of service or potentially execute code.

- **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:** 21 Oct 2024
- **Updated:** 5 Aug 2026
- **Also known as:** DEBIAN-CVE-2022-48956, GHSA-h52p-rfc4-3rcf, UBUNTU-CVE-2022-48956

## What is CVE-2022-48956?

CVE-2022-48956 is a high-severity use after free vulnerability in Linux kernel, published on 21 Oct 2024. 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:

ipv6: avoid use-after-free in ip6_fragment()

Blamed commit claimed rcu_read_lock() was held by ip6_fragment() callers.

It seems to not be always true, at least for UDP stack.

syzbot reported:

BUG: KASAN: use-after-free in ip6_dst_idev include/net/ip6_fib.h:245 [inline]
BUG: KASAN: use-after-free in ip6_fragment+0x2724/0x2770 net/ipv6/ip6_output.c:951
Read of size 8 at addr ffff88801d403e80 by task syz-executor.3/7618

CPU: 1 PID: 7618 Comm: syz-executor.3 Not tainted 6.1.0-rc6-syzkaller-00012-g4312098baf37 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:284 [inline]
 print_report+0x15e/0x45d mm/kasan/report.c:395
 kasan_report+0xbf/0x1f0 mm/kasan/report.c:495
 ip6_dst_idev include/net/ip6_fib.h:245 [inline]
 ip6_fragment+0x2724/0x2770 net/ipv6/ip6_output.c:951
 __ip6_finish_output net/ipv6/ip6_output.c:193 [inline]
 ip6_finish_output+0x9a3/0x1170 net/ipv6/ip6_output.c:206
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip6_output+0x1f1/0x540 net/ipv6/ip6_output.c:227
 dst_output include/net/dst.h:445 [inline]
 ip6_local_out+0xb3/0x1a0 net/ipv6/output_core.c:161
 ip6_send_skb+0xbb/0x340 net/ipv6/ip6_output.c:1966
 udp_v6_send_skb+0x82a/0x18a0 net/ipv6/udp.c:1286
 udp_v6_push_pending_frames+0x140/0x200 net/ipv6/udp.c:1313
 udpv6_sendmsg+0x18da/0x2c80 net/ipv6/udp.c:1606
 inet6_sendmsg+0x9d/0xe0 net/ipv6/af_inet6.c:665
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg+0xd3/0x120 net/socket.c:734
 sock_write_iter+0x295/0x3d0 net/socket.c:1108
 call_write_iter include/linux/fs.h:2191 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x9ed/0xdd0 fs/read_write.c:584
 ksys_write+0x1ec/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fde3588c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fde365b6168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fde359ac050 RCX: 00007fde3588c0d9
RDX: 000000000000ffdc RSI: 00000000200000c0 RDI: 000000000000000a
RBP: 00007fde358e7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fde35acfb1f R14: 00007fde365b6300 R15: 0000000000022000
 </TASK>

Allocated by task 7618:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 __kasan_slab_alloc+0x82/0x90 mm/kasan/common.c:325
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slab.h:737 [inline]
 slab_alloc_node mm/slub.c:3398 [inline]
 slab_alloc mm/slub.c:3406 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3413 [inline]
 kmem_cache_alloc+0x2b4/0x3d0 mm/slub.c:3422
 dst_alloc+0x14a/0x1f0 net/core/dst.c:92
 ip6_dst_alloc+0x32/0xa0 net/ipv6/route.c:344
 ip6_rt_pcpu_alloc net/ipv6/route.c:1369 [inline]
 rt6_make_pcpu_route net/ipv6/route.c:1417 [inline]
 ip6_pol_route+0x901/0x1190 net/ipv6/route.c:2254
 pol_lookup_func include/net/ip6_fib.h:582 [inline]
 fib6_rule_lookup+0x52e/0x6f0 net/ipv6/fib6_rules.c:121
 ip6_route_output_flags_noref+0x2e6/0x380 net/ipv6/route.c:2625
 ip6_route_output_flags+0x76/0x320 net/ipv6/route.c:2638
 ip6_route_output include/net/ip6_route.h:98 [inline]
 ip6_dst_lookup_tail+0x5ab/0x1620 net/ipv6/ip6_output.c:1092
 ip6_dst_lookup_flow+0x90/0x1d0 net/ipv6/ip6_output.c:1222
 ip6_sk_dst_lookup_flow+0x553/0x980 net/ipv6/ip6_output.c:1260
 udpv6_sendmsg+0x151d/0x2c80 net/ipv6/udp.c:1554
 inet6_sendmsg+0x9d/0xe0 net/ipv6/af_inet6.c:665
 sock_sendmsg_nosec n
---truncated---

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2022-48956?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-48956?

Apply the vendor's patch.

## Is CVE-2022-48956 being exploited?

There is no known exploitation of CVE-2022-48956 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-48956 and fix it if it is affected.

What it is: CVE-2022-48956 is a high-severity use after free vulnerability in Linux kernel, published on 21 Oct 2024. 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-2022-48956 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2022-48956/ (Markdown: https://insights.sbomify.com/CVE-2022-48956/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-48956
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-48956
- OSV: https://osv.dev/vulnerability/CVE-2022-48956

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-48956/
Summaries are generated and may contain mistakes; the official description above is the record.