# CVE-2025-68813: ipvs: fix ipv4 null-ptr-deref in route error path

> A null pointer dereference in the Linux kernel IPVS module allows remote attackers to cause a denial of service via crafted network packets.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Jan 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2025-68813, DEBIAN-CVE-2025-68813, GHSA-r9w6-9rjj-r9c5, ROOT-OS-DEBIAN-11-CVE-2025-68813, ROOT-OS-DEBIAN-12-CVE-2025-68813, ROOT-OS-DEBIAN-13-CVE-2025-68813, ROOT-OS-UBUNTU-2204-CVE-2025-68813, ROOT-OS-UBUNTU-2404-CVE-2025-68813, UBUNTU-CVE-2025-68813

## What is CVE-2025-68813?

CVE-2025-68813 is a vulnerability in Linux, published on 13 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

ipvs: fix ipv4 null-ptr-deref in route error path

The IPv4 code path in __ip_vs_get_out_rt() calls dst_link_failure()
without ensuring skb->dev is set, leading to a NULL pointer dereference
in fib_compute_spec_dst() when ipv4_link_failure() attempts to send
ICMP destination unreachable messages.

The issue emerged after commit ed0de45a1008 ("ipv4: recompile ip options
in ipv4_link_failure") started calling __ip_options_compile() from
ipv4_link_failure(). This code path eventually calls fib_compute_spec_dst()
which dereferences skb->dev. An attempt was made to fix the NULL skb->dev
dereference in commit 0113d9c9d1cc ("ipv4: fix null-deref in
ipv4_link_failure"), but it only addressed the immediate dev_net(skb->dev)
dereference by using a fallback device. The fix was incomplete because
fib_compute_spec_dst() later in the call chain still accesses skb->dev
directly, which remains NULL when IPVS calls dst_link_failure().

The crash occurs when:
1. IPVS processes a packet in NAT mode with a misconfigured destination
2. Route lookup fails in __ip_vs_get_out_rt() before establishing a route
3. The error path calls dst_link_failure(skb) with skb->dev == NULL
4. ipv4_link_failure() → ipv4_send_dest_unreach() →
   __ip_options_compile() → fib_compute_spec_dst()
5. fib_compute_spec_dst() dereferences NULL skb->dev

Apply the same fix used for IPv6 in commit 326bf17ea5d4 ("ipvs: fix
ipv6 route unreach panic"): set skb->dev from skb_dst(skb)->dev before
calling dst_link_failure().

KASAN: null-ptr-deref in range [0x0000000000000328-0x000000000000032f]
CPU: 1 PID: 12732 Comm: syz.1.3469 Not tainted 6.6.114 #2
RIP: 0010:__in_dev_get_rcu include/linux/inetdevice.h:233
RIP: 0010:fib_compute_spec_dst+0x17a/0x9f0 net/ipv4/fib_frontend.c:285
Call Trace:
  <TASK>
  spec_dst_fill net/ipv4/ip_options.c:232
  spec_dst_fill net/ipv4/ip_options.c:229
  __ip_options_compile+0x13a1/0x17d0 net/ipv4/ip_options.c:330
  ipv4_send_dest_unreach net/ipv4/route.c:1252
  ipv4_link_failure+0x702/0xb80 net/ipv4/route.c:1265
  dst_link_failure include/net/dst.h:437
  __ip_vs_get_out_rt+0x15fd/0x19e0 net/netfilter/ipvs/ip_vs_xmit.c:412
  ip_vs_nat_xmit+0x1d8/0xc80 net/netfilter/ipvs/ip_vs_xmit.c:764

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-68813?


## How do I fix CVE-2025-68813?

Apply the vendor's patch.

## Is CVE-2025-68813 being exploited?

There is no known exploitation of CVE-2025-68813 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68813 and fix it if it is affected.

What it is: CVE-2025-68813 is a vulnerability in Linux, published on 13 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-68813 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-2025-68813/ (Markdown: https://insights.sbomify.com/CVE-2025-68813/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68813
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68813
- OSV: https://osv.dev/vulnerability/CVE-2025-68813

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68813/
Summaries are generated and may contain mistakes; the official description above is the record.