VulnerabilityPublished 15 Aug 2026Updated 9 Oct 2026

CVE-2026-72428: Linux kernel · bpf: Fix stack slot index in nospec checks

Affects Linux kernelSource GCVE Database

Not known to be exploited · fixed in 5.15.0-1117.124~20.04.1 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +41

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Aug 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.

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What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSlinux`pkg:deb/ubuntu/linux?arch=source&distro=resolute`Other threats	Affected <7.0.0-38.38	Fixed in 7.0.0-38.38
Ubuntu 26.04 LTSlinux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=resolute`Other threats	Affected <7.0.0-1014.14	Fixed in 7.0.0-1014.14
Ubuntu 26.04 LTSlinux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=resolute`Other threats	Affected <7.0.0-1017.17	Fixed in 7.0.0-1017.17
Ubuntu 26.04 LTSlinux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resolute`Other threats	Affected <7.0.0-1016.16	Fixed in 7.0.0-1016.16
Ubuntu 26.04 LTSlinux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=resolute`Other threats	Affected <7.0.0-1014.14	Fixed in 7.0.0-1014.14
Ubuntu 26.04 LTSlinux-gke`pkg:deb/ubuntu/linux-gke?arch=source&distro=resolute`Other threats	Affected <7.0.0-1008.9	Fixed in 7.0.0-1008.9

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

AI-suggested

A patch is available and should be applied to affected Linux kernel versions to correct the stack slot indexing in the nospec checks. The vendor advisory confirms the issue has been resolved in updated kernel releases. Users should update to the fixed versions listed in the advisory to mitigate this vulnerability.

Description

A vulnerability in the Linux kernel's BPF subsystem related to stack slot indexing in speculative execution (Spectre v4) sanitization checks has been fixed. The issue involved inconsistent indexing of stack slots during nospec checks, potentially leaving some stack writes without proper sanitization. This flaw was addressed by aligning the slot index used in the sanitization pre-check with the write path. Multiple specific Linux kernel versions are affected. A patch is available to resolve this issue.

Impact

The vulnerability affects the Linux kernel's BPF subsystem's speculative execution sanitization, potentially allowing bypass of Spectre v4 mitigations on stack writes. While no known exploits are reported in the wild, the flaw could theoretically weaken security guarantees against speculative execution attacks. The impact is considered medium severity, as it relates to speculative execution sanitization correctness rather than direct code execution or privilege escalation.

Summary

The Linux kernel BPF subsystem had a vulnerability (CVE-2026-72428) where the function check_stack_write_fixed_off() computed the byte slot for fixed-offset stack writes differently than the Spectre v4 sanitization pre-check used. Specifically, the pre-check scanned bytes using slot_type[i], while the write path updated slot_type[] with a different index calculation. This mismatch could cause the second half of a 4-byte write to be left without the necessary nospec_result sanitization, potentially undermining Spectre v4 mitigations. The fix ensures the sanitization pre-check uses the same slot index as the write path, correcting the inconsistency.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Oct 2026, 08:42 UTC

Technical details

References

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