VulnerabilityPublished 25 Jul 2026Updated 19 Oct 2026

CVE-2026-64450: Linux kernel · Out-of-bounds Read

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 9.1 Critical · fixed in f333b6851bdf326fd2134133272dbbed0c94d921 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 23:07 UTC

CVSS 3.1 base score

9.1Critical

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

EPSS

0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers can reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch

Available – fixed in f333b6851bdf326fd2134133272dbbed0c94d921, a21ed5064217cc33726da6c7ef1a520eba43aea1, 055663d21dc4336f67933ab26bef3c5934be6324 +5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
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: None: There is no loss of integrity within 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 25 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.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ d7626b5acff9227e2a65da636a53e09bdafdc0aa, < f333b6851bdf326fd2134133272dbbed0c94d921	Fixed in f333b6851bdf326fd2134133272dbbed0c94d921
LinuxLinux	Affected ≥ d7626b5acff9227e2a65da636a53e09bdafdc0aa, < a21ed5064217cc33726da6c7ef1a520eba43aea1	Fixed in a21ed5064217cc33726da6c7ef1a520eba43aea1
LinuxLinux	Affected ≥ d7626b5acff9227e2a65da636a53e09bdafdc0aa, < 055663d21dc4336f67933ab26bef3c5934be6324	Fixed in 055663d21dc4336f67933ab26bef3c5934be6324
LinuxLinux	Affected ≥ d7626b5acff9227e2a65da636a53e09bdafdc0aa, < 74b45af86a767594ba52330cd440ea84e24d700d	Fixed in 74b45af86a767594ba52330cd440ea84e24d700d
LinuxLinux	Affected ≥ d7626b5acff9227e2a65da636a53e09bdafdc0aa, < 016f5995c37a5a2c45198308f830f244517d70b7	Fixed in 016f5995c37a5a2c45198308f830f244517d70b7
LinuxLinux	Affected ≥ d7626b5acff9227e2a65da636a53e09bdafdc0aa, < 9a51115fcdc78687c8852bf93a1db3951dbb223b	Fixed in 9a51115fcdc78687c8852bf93a1db3951dbb223b

AI-suggested

A fix is available and has been applied in multiple Linux kernel commits after version 5.8. Users and administrators should update to a fixed kernel version containing these commits. No additional mitigation is required as the fix ensures that oversized broadcast Gap ACK blocks are discarded and not processed.

Description

CVE-2026-64450 is a critical out-of-bounds read vulnerability in the Linux kernel's TIPC protocol broadcast handling. The flaw occurs because the broadcast path does not properly verify that a Gap ACK blocks record fits within the message data area, leading to an out-of-bounds read when copying data. This can cause kernel memory corruption and potentially a denial of service. The issue affects Linux kernel version 5.8 and has been fixed in subsequent commits.

Impact

An attacker controlling a TIPC neighbor can send a specially crafted broadcast STATE_MSG with an oversized Gap ACK record, causing the kernel to perform an out-of-bounds read. This can lead to kernel memory corruption and a denial of service (crash). The CVSS score is 9.1 (critical) with network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality and availability.

Summary

The vulnerability in the Linux kernel's TIPC protocol involves an out-of-bounds read triggered by malformed broadcast Gap ACK blocks. The function tipc_get_gap_ack_blks() verifies the consistency of the record's length field with its counts but does not check if the record fits within the message data area. While the unicast path bounds this properly, the broadcast path discards the size and copies data using an attacker-controlled count, resulting in a read beyond the allocated buffer. This leads to a kernel slab-out-of-bounds error detected by KASAN. The fix bounds the record size against the message data size and discards oversized messages to prevent processing invalid data.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 23:07 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

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