VulnerabilityPublished 24 Sep 2026Updated 20 Oct 2026

CVE-2026-97420: Linux kernel · bpf: NUL-terminate replaced sysctl value

Affects Linux kernelSource GCVE Database

Not known to be exploited.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-xwmh-p524-56rv

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSlinux`pkg:deb/ubuntu/linux?arch=source&distro=resolute`Other threats	Affected 6.17.0-5.5 – 7.0.0-38.38 23 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=resolute`Other threats	Affected 6.17.0-1003.3 – 7.0.0-1017.17 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resolute`Other threats	Affected 7.0.0-1003.3 – 7.0.0-1016.16 9 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 13 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gke`pkg:deb/ubuntu/linux-gke?arch=source&distro=resolute`Other threats	Affected 7.0.0-1002.3 – 7.0.0-1008.9 6 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix has been applied to append a terminating NUL byte after replaced sysctl values in the bpf_sysctl_set_new_value() helper. Users should update to a Linux kernel version that includes this fix to prevent out-of-bounds memory access. Since this is a kernel-level fix, upgrading the kernel to a patched version is the recommended remediation. Patch status is not explicitly stated in the input data; users should consult their Linux distribution or vendor advisory for the fixed kernel versions.

Description

A vulnerability in the Linux kernel's BPF subsystem related to sysctl value replacement was resolved. The issue involved the bpf_sysctl_set_new_value() helper not appending a NUL terminator after replacing a sysctl value, which could lead to out-of-bounds memory access by downstream parsers. This was confirmed by a kernel address sanitizer (KASAN) report indicating slab-out-of-bounds reads. The fix appends a terminating NUL byte to the replacement buffer, restoring expected sysctl semantics and preventing the out-of-bounds access.

Impact

The vulnerability could cause out-of-bounds memory reads in kernel space when parsing sysctl values replaced by BPF programs, potentially leading to kernel crashes or undefined behavior. The issue was detected by KASAN during testing but there are no known exploits in the wild. The impact is limited to kernel stability and memory safety during sysctl value replacement via BPF.

Summary

The Linux kernel vulnerability CVE-2026-97420 concerns the bpf_sysctl_set_new_value() helper function used when writing to sysctls. While proc_sys_call_handler() guarantees that buffers passed to proc handlers are NUL-terminated, the helper function replaced sysctl values without appending a terminating NUL byte, copying only buf_len bytes. This omission allowed downstream parsers to access memory out-of-bounds, as demonstrated by a KASAN slab-out-of-bounds error during testing with a cgroup/sysctl BPF program targeting /proc/sys/net/core/flow_limit_cpu_bitmap. The fix appends a '\0' byte after the replaced value, ensuring proper termination and preventing the vulnerability.

GCVE source: db.gcve.eu
OSV ID: UBUNTU-CVE-2026-97420
Osv Schema Version: 1.7.0
Ecosystems: Ubuntu:Pro:14.04:LTS, Ubuntu:Pro:16.04:LTS, Ubuntu:16.04:LTS, Ubuntu:Pro:FIPS:16.04:LTS, Ubuntu:Pro:18.04:LTS, Ubuntu:18.04:LTS, Ubuntu:Pro:FIPS-updates:18.04:LTS, Ubuntu:Pro:FIPS:18.04:LTS, Ubuntu:Pro:20.04:LTS, Ubuntu:20.04:LTS, Ubuntu:Pro:FIPS-updates:20.04:LTS, Ubuntu:Pro:FIPS:20.04:LTS, Ubuntu:22.04:LTS, Ubuntu:Nvidia-BlueField:22.04:LTS, Ubuntu:Pro:FIPS-preview:22.04:LTS, Ubuntu:Pro:FIPS-updates:22.04:LTS, Ubuntu:Pro:Realtime:22.04:LTS, Ubuntu:24.04:LTS, Ubuntu:Nvidia-BlueField:24.04:LTS, Ubuntu:Pro:FIPS-updates:24.04:LTS, Ubuntu:Pro:Realtime:24.04:LTS, Ubuntu:26.04:LTS

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Oct 2026, 15:37 UTC

Technical details

References

Community reviews

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