What breaks and who should care
If your scanner has just raised CVE-2017-1000253, the alarm is about a local privilege‑escalation flaw in the Linux kernel. Any system that runs an affected kernel build could let an unprivileged user gain root rights. System administrators, security engineers, and anyone who maintains Linux hosts need to act now.
Related remediation guides
Other vulnerabilities in the same family or affecting the same products:
- CVE-2026-43284 – Linux kernel ESP‑in‑UDP in‑place decryption flaw
- CVE-2024-49039 – Windows Task Scheduler privilege escalation fix guide
- CVE-2021-43226 – Windows CLFS Driver Privilege Escalation – What You Need to Do
CISA’s confirmed actively-exploited flaws are tracked on our Known Exploited Vulnerabilities tracker, refreshed daily.
What is CVE-2017-1000253?
The vulnerability is a stack buffer corruption in the function that loads ELF binaries. The kernel treats the stack as position‑independent executable (PIE) code, and a specially crafted ELF file can overflow a buffer, corrupting the stack and allowing code execution with kernel privileges. In plain terms, a local attacker can run a tiny program that tricks the kernel into running their code as root.
The National Vulnerability Database assigns it a CVSS base score of 7.8, classifying it as high severity. The score reflects the ease of exploitation (local attacker, no authentication required) and the impact (full system compromise).
Confirmed exploits have been observed in the wild, and the United States Cybersecurity and Infrastructure Security Agency (CISA) lists it in the Known Exploited Vulnerabilities catalogue. Ransomware groups have also been recorded using this flaw to gain initial footholds on vulnerable machines.
How does the flaw work?
The kernel’s ELF loader parses the executable’s header, allocates a stack buffer, and copies data from the ELF file into that buffer. The code assumes the data will never exceed the buffer size, but the check is missing for a particular field when the binary is built as PIE. An attacker can craft an ELF file where that field contains more data than the buffer can hold, causing an overflow.
When the overflow occurs, the attacker can overwrite the return address on the stack. The kernel then returns to attacker‑controlled code, which runs with kernel privileges. Because the exploit works entirely in user space, it does not require any network access or special permissions – any local account can trigger it.
The exact details of the payload and the exact offset values are not publicly disclosed in the NVD entry. What is clear is that the bug resides in the core ELF loading path, meaning every Linux distribution that ships the affected kernel version is potentially vulnerable.
Am I affected?
The only reliable way to know is to check the kernel version you are running and compare it with the ranges listed in the table below. Do not rely on the version string alone; the table shows the exact branches that received a fix.
Run one of the following commands on the host in question:
uname -rcat /proc/version
Copy the output and look for the version identifier. Then locate that identifier in the table below. If the identifier falls within an affected range, the system is vulnerable and needs remediation.
What does the table below show?
The table lists every kernel series that contains the flaw and the first release in that series that includes the fix. For each major branch you will see a “fixed in” entry. Upgrading to any release at or beyond that point removes the vulnerable code.
How to fix it
The recommended remediation is to upgrade the kernel to the patched release for your branch. Most modern distributions provide kernel updates through their package manager. Follow the steps that match your package system.
Debian‑based systems (apt)
- Refresh the package index:
sudo apt update - Upgrade the kernel package:
sudo apt install linux-image-$(uname -r)(replace the placeholder with the exact package name shown byapt list --upgradable) - Reboot to load the new kernel:
sudo reboot
Red Hat‑based systems (yum / dnf)
- Check for updates:
sudo yum check-update kernelorsudo dnf check-update kernel - Install the latest kernel:
sudo yum install kernelorsudo dnf install kernel - Reboot:
sudo reboot
SUSE systems (zypper)
- Refresh repositories:
sudo zypper refresh - Upgrade the kernel:
sudo zypper install --type=package kernel-default - Reboot:
sudo reboot
If you run a distribution that ships a custom kernel (e.g. embedded devices, cloud images, or hardened builds), locate the vendor’s security advisory and apply the provided binary or rebuild the kernel with the vendor’s patch set.
If a patched kernel is not available
In some environments – for example, legacy appliances that cannot be upgraded – you may have to rely on mitigations until a fix can be applied.
- Restrict local access: ensure only trusted users have shell accounts. Use multi‑factor authentication for any privileged login.
- Enable SELinux or AppArmor in enforcing mode. These MAC frameworks can block the execution of untrusted ELF binaries, reducing the chance an attacker can trigger the vulnerable loader.
- Consider using a kernel hardening patch set (e.g. grsecurity or a similar project) that disables execution of user‑controlled code on the kernel stack.
- Audit binaries that are allowed to run with set‑uid or set‑gid bits. Remove unnecessary privileged binaries to shrink the attack surface.
Document the limitation and plan a migration path to a supported kernel as soon as possible. Continuing to run an unpatched kernel after a known exploit is publicly available puts the host at high risk of compromise.
Verification after remediation
Once you have rebooted into the new kernel, confirm the running version again with uname -r. Cross‑reference the output with the table below to ensure the version is at or beyond the fixed release.
Optionally, run a quick local scan with a tool that checks for CVE-2017-1000253. If the scanner reports the host as clean, you have successfully mitigated the vulnerability.
What to do if you suspect compromise
Because the flaw grants root privileges, any successful exploitation will leave traces that may be hard to spot. Follow your incident‑response playbook:
- Collect volatile data (process list, network sockets, logged‑in users) with
ps aux,netstat -tulpn, andw. - Take a forensic image of the disk for later analysis.
- Isolate the host from the network to stop further movement.
- Apply the kernel upgrade immediately, even if you plan to rebuild the system from scratch.
- Review logs for suspicious ELF loading events; look for unusual file names or execution paths.
After containment, rebuild the system from known‑good sources, rotate all credentials, and monitor for re‑infection.
Summary
CVE-2017-1000253 is a high‑severity local privilege‑escalation bug in the Linux kernel’s ELF loader. It has been exploited in the wild and is used by ransomware groups. The fix is straightforward: upgrade the kernel to the patched release for your branch, as shown in the table below. If you cannot upgrade, apply hardening measures, limit local accounts, and plan a migration as soon as possible. Verify the running kernel after reboot, and if you see any signs of compromise, follow your incident‑response procedures.
Affected and fixed kernel releases
The table below is generated automatically from the National Vulnerability Database and lists every kernel series that contains the flaw and the first release that includes the fix. Use it as the definitive source for determining whether your system needs an upgrade.
Affected versions
Straight from the NVD record for CVE-2017-1000253. If your build is inside one of these ranges, treat it as vulnerable.
| Product | Affected range | Fixed in |
|---|---|---|
linux_kernel |
2.6.25 up to 3.2.70 | 3.2.70 |
linux_kernel |
3.3 up to 3.4.109 | 3.4.109 |
linux_kernel |
3.5 up to 3.10.77 | 3.10.77 |
linux_kernel |
3.11 up to 3.12.43 | 3.12.43 |
linux_kernel |
3.13 up to 3.14.41 | 3.14.41 |
linux_kernel |
3.15 up to 3.16.35 | 3.16.35 |
linux_kernel |
3.17 up to 3.18.14 | 3.18.14 |
linux_kernel |
3.19 up to 3.19.7 | 3.19.7 |
linux_kernel |
4.0 up to 4.0.2 | 4.0.2 |
