VulnerabilityPublished 19 Jul 2026

CVE-2026-64046: Linux kernel · net: tls: prevent chain-after-chain in plain text SG

Source GCVE Database

Authoritative record:CVE-2026-64046· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in ff26a0e8377dec07e4a7230db7675bed1b9a6d03 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

9.8Critical

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in ff26a0e8377dec07e4a7230db7675bed1b9a6d03, b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36, af855f4c966afafef74faf8390c7b86568c0d46d +6

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jul 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-3mwm-pxvj-5v4x

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=5.4.14 <5.5	Fixed in ff26a0e8377dec07e4a7230db7675bed1b9a6d03 b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36 af855f4c966afafef74faf8390c7b86568c0d46d acdc12b71c9aa4be5dcd2c8062753c6d2033e235 410351158dfef2d67fea6603680b3a6013c6ed9d 91359966e247c0244c66d50bbb8e74aefa4321c3 929b1548e63ac72e104c07d8ee8cbbeeba2fa89a 49a5faaa471ddcd37b6893970c9916eb836e7c31 5.5
LinuxLinux	Affected =5.5	Fixed in–

AI-suggested

A fix has been applied in the Linux kernel to prevent the chain-after-chain condition in the TLS scatterlist handling. Users should update to a Linux kernel version that includes this fix.

Description

In the Linux kernel, the following vulnerability has been resolved: net: tls: prevent chain-after-chain in plain text SG Sashiko points out that if end = 0 (start != 0) the current code will create a chain link to content type right after the wrap link: This would create a chain where the wrap link points directly to another chain link. The scatterlist API sg_next iterator does not recursively resolve consecutive chain links. meaning this is illegal input to crypto. The wrapping link is unnecessary if end = 0. end is the entry after the last one used so end = 0 means there's nothing pushed after the wrap: end start i v v v [ ]...[ ][ d ][ d ][ d ][ d ][rsv for wrap] Skip the wrapping in this case. TLS 1.3 can use the "wrapping slot" for it's chaining if end = 0. This avoids the chain-after-chain. Move the wrap chaining before marking END and chaining off content type, that feels like more logical ordering to me, but should not matter from functional perspective.

Impact

The vulnerability could lead to illegal input being passed to the kernel crypto subsystem during TLS processing, potentially causing errors or unexpected behavior in TLS 1.3 network traffic handling. No known exploits are reported in the wild. The exact impact on confidentiality, integrity, or availability is not detailed in the provided data.

Summary

The Linux kernel TLS implementation had a vulnerability where the scatterlist API could be given illegal input due to a chain-after-chain condition. When the 'end' pointer was zero but 'start' was not, the code created a wrap link that pointed directly to another chain link, which the scatterlist iterator does not handle recursively. This could cause improper chaining in the crypto processing of TLS data. The patch changes the logic to skip the wrapping link if 'end' is zero, avoiding the chain-after-chain scenario. The fix also reorders wrap chaining steps for logical clarity without functional impact.

References

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