VulnerabilityPublished 23 Oct 2026

CVE-2026-99042: Linux kernel · io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6

Source GCVE Database

Authoritative record:CVE-2026-99042· High 8.4

Not known to be exploited · CVSS 8.4 High : upgrade to aa5d5f8e502318e783545ba5d04bb40130b83e20 or 596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5 soon.

Data as of 26 Oct 2026, 14:05 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 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in aa5d5f8e502318e783545ba5d04bb40130b83e20, 596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5

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 23 Oct 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-cg89-27g3-43v4

What to do

Upgrade Linux kernel to aa5d5f8e502318e783545ba5d04bb40130b83e20 or 596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 899bea8248cee35d54760a5e7d61a76af8e64411, < aa5d5f8e502318e783545ba5d04bb40130b83e20	Fixed in aa5d5f8e502318e783545ba5d04bb40130b83e20
LinuxLinux	Affected ≥ 899bea8248cee35d54760a5e7d61a76af8e64411, < 596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5	Fixed in 596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5
LinuxLinux	Affected =7.2	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to correct the length threshold used in io_connect_bpf_populate(), aligning it with SIN6_LEN_RFC2133 (24 bytes). Users should update to a kernel version that includes this patch (e.g., 7.3-rc6 or later). No additional mitigation is required beyond applying the official fix.

Description

A vulnerability in the Linux kernel's io_uring/net subsystem was resolved that involved incorrect handling of IPv6 sockaddr length in connection filtering. The issue caused connect filters to see zeroed port and address fields when the sockaddr_in6 length was 24 bytes (SIN6_LEN_RFC2133), allowing filters that deny connections based on port or address to be bypassed. The fix aligns the length threshold to SIN6_LEN_RFC2133, ensuring filters correctly see the real destination address and port.

References

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