# CVE-2025-68259: KVM: SVM: Don't skip unrelated instruction if INT3/INTO is replaced

> A race condition in KVM SVM allows a local attacker to cause guest kernel panics by triggering incorrect instruction decoding during code patching.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-72497, BELL-CVE-2025-68259, DEBIAN-CVE-2025-68259, GHSA-xgvr-xgq4-2mpp, ROOT-OS-DEBIAN-12-CVE-2025-68259, ROOT-OS-DEBIAN-13-CVE-2025-68259, ROOT-OS-UBUNTU-2404-CVE-2025-68259, UBUNTU-CVE-2025-68259

## What is CVE-2025-68259?

CVE-2025-68259 is a denial of service vulnerability in Linux, published on 16 Dec 2025. 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:

KVM: SVM: Don't skip unrelated instruction if INT3/INTO is replaced

When re-injecting a soft interrupt from an INT3, INT0, or (select) INTn
instruction, discard the exception and retry the instruction if the code
stream is changed (e.g. by a different vCPU) between when the CPU
executes the instruction and when KVM decodes the instruction to get the
next RIP.

As effectively predicted by commit 6ef88d6e36c2 ("KVM: SVM: Re-inject
INT3/INTO instead of retrying the instruction"), failure to verify that
the correct INTn instruction was decoded can effectively clobber guest
state due to decoding the wrong instruction and thus specifying the
wrong next RIP.

The bug most often manifests as "Oops: int3" panics on static branch
checks in Linux guests.  Enabling or disabling a static branch in Linux
uses the kernel's "text poke" code patching mechanism.  To modify code
while other CPUs may be executing that code, Linux (temporarily)
replaces the first byte of the original instruction with an int3 (opcode
0xcc), then patches in the new code stream except for the first byte,
and finally replaces the int3 with the first byte of the new code
stream.  If a CPU hits the int3, i.e. executes the code while it's being
modified, then the guest kernel must look up the RIP to determine how to
handle the #BP, e.g. by emulating the new instruction.  If the RIP is
incorrect, then this lookup fails and the guest kernel panics.

The bug reproduces almost instantly by hacking the guest kernel to
repeatedly check a static branch[1] while running a drgn script[2] on
the host to constantly swap out the memory containing the guest's TSS.

[1]: https://gist.github.com/osandov/44d17c51c28c0ac998ea0334edf90b5a
[2]: https://gist.github.com/osandov/10e45e45afa29b11e0c7209247afc00b

## Which versions are affected by CVE-2025-68259?


## How do I fix CVE-2025-68259?

Apply the vendor's patch.

## Is CVE-2025-68259 being exploited?

There is no known exploitation of CVE-2025-68259 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68259 and fix it if it is affected.

What it is: CVE-2025-68259 is a denial of service vulnerability in Linux, published on 16 Dec 2025. 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-2025-68259 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-2025-68259/ (Markdown: https://insights.sbomify.com/CVE-2025-68259/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68259
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68259
- OSV: https://osv.dev/vulnerability/CVE-2025-68259

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68259/
Summaries are generated and may contain mistakes; the official description above is the record.