VulnerabilityPublished 17 Sep 2026Updated 21 Oct 2026

CVE-2026-90347: Linux kernel · arm64: ptrace: Keep 'orig_x0' in-sync with x0 on syscall entry

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 8.4 High · fixed in f433869f23841a50455c4087d85540d5b4d37cde : patch Linux kernel soon.

Data as of 26 Oct 2026, 20:04 UTC

CVSS 3.1 base score

8.4High

How severe the flaw is on the 0–10 CVSS scale.

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.
Patch: Available – fixed in f433869f23841a50455c4087d85540d5b4d37cde, e9e2854fcff5733ffc607e8ecc87e0e591ab41fd, ce17c651a90e242ad48df0df89b1e4cebcda5e14 +2

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Changed
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 17 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.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a5cd110cb8369d6b37ef5ccfe56b3fa1338c9615, < f433869f23841a50455c4087d85540d5b4d37cde	Fixed in f433869f23841a50455c4087d85540d5b4d37cde
LinuxLinux	Affected ≥ a5cd110cb8369d6b37ef5ccfe56b3fa1338c9615, < e9e2854fcff5733ffc607e8ecc87e0e591ab41fd	Fixed in e9e2854fcff5733ffc607e8ecc87e0e591ab41fd
LinuxLinux	Affected ≥ a5cd110cb8369d6b37ef5ccfe56b3fa1338c9615, < ce17c651a90e242ad48df0df89b1e4cebcda5e14	Fixed in ce17c651a90e242ad48df0df89b1e4cebcda5e14
LinuxLinux	Affected ≥ a5cd110cb8369d6b37ef5ccfe56b3fa1338c9615, < 332c9c1a148d0425326989c1187face8f6b2a60c	Fixed in 332c9c1a148d0425326989c1187face8f6b2a60c
LinuxLinux	Affected ≥ a5cd110cb8369d6b37ef5ccfe56b3fa1338c9615, < 88b839ce497ccb1ff92f7ae742c78dd2937ba572	Fixed in 88b839ce497ccb1ff92f7ae742c78dd2937ba572
LinuxLinux	Affected =4.8	Fixed in–

AI-suggested

A fix is available and has been applied in several Linux kernel commits identified by hashes f433869f23841a50455c4087d85540d5b4d37cde, e9e2854fcff5733ffc607e8ecc87e0e591ab41fd, ce17c651a90e242ad48df0df89b1e4cebcda5e14, 332c9c1a148d0425326989c1187face8f6b2a60c, and 88b839ce497ccb1ff92f7ae742c78dd2937ba572. Users and administrators should update their Linux kernel to a version including these fixes. No additional mitigations are indicated by the vendor advisory.

Description

CVE-2026-90347 is a high-severity vulnerability in the Linux kernel affecting arm64 architectures. It involves the ptrace subsystem where the 'orig_x0' register was not kept in sync with the 'x0' register on syscall entry, allowing a tracer to manipulate the first syscall argument without proper seccomp or audit checks. This issue was partially addressed in a prior commit but required further correction to ensure 'orig_x0' is updated correctly during ptrace and seccomp interactions. The vulnerability has been fixed in several Linux kernel commits.

Impact

The vulnerability allows a local attacker with ptrace capabilities to manipulate the first syscall argument without being subjected to seccomp or audit checks, potentially bypassing security policies and leading to privilege escalation or unauthorized system calls. The CVSS 3.1 score is 8.4 (high), reflecting the local attack vector with low complexity, requiring low privileges, no user interaction, and resulting in high confidentiality and integrity impact but no availability impact.

Summary

This vulnerability concerns the arm64 ptrace implementation in the Linux kernel. The problem arises because the 'orig_x0' register, which holds the original first syscall argument, was not updated in sync with the 'x0' register when a tracer modifies 'x0' during syscall entry. This desynchronization allowed a tracer to alter the syscall argument without triggering seccomp or audit checks, potentially bypassing security mechanisms. The initial fix (commit e057b9477232) was incomplete as it did not update 'orig_x0' between ptrace exit and seccomp filter re-evaluation. The final fix moves synchronization logic into ptrace general-purpose register and syscall setting code to maintain 'orig_x0' consistency on syscall entry. The vulnerability affects Linux kernel version 4.8 and was resolved in multiple subsequent commits.

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Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 20:04 UTC

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