VulnerabilityPublished 18 Oct 2026Updated 24 Oct 2026

CVE-2026-98479: Linux kernel · scsi: libiscsi_tcp: Check the data direction of a Data-In PDU

Source GCVE Database

Authoritative record:CVE-2026-98479· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in ee56b5e18f566c0b5a183379dcd63d402cebf2f8 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in ee56b5e18f566c0b5a183379dcd63d402cebf2f8, e3b25bf2cf2496e85bc05b33360faf9fdf880e03, de96dc11aee0d058927bff94a168e3c5c46483e2 +5

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

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

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: None: There is no loss of confidentiality within the impacted component.
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 18 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-m9q9-jv5w-f7p7

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a081c13e39b5c17052a7b46fafa61019c4c110ff, < ee56b5e18f566c0b5a183379dcd63d402cebf2f8	Fixed in ee56b5e18f566c0b5a183379dcd63d402cebf2f8
LinuxLinux	Affected ≥ a081c13e39b5c17052a7b46fafa61019c4c110ff, < e3b25bf2cf2496e85bc05b33360faf9fdf880e03	Fixed in e3b25bf2cf2496e85bc05b33360faf9fdf880e03
LinuxLinux	Affected ≥ a081c13e39b5c17052a7b46fafa61019c4c110ff, < de96dc11aee0d058927bff94a168e3c5c46483e2	Fixed in de96dc11aee0d058927bff94a168e3c5c46483e2
LinuxLinux	Affected ≥ a081c13e39b5c17052a7b46fafa61019c4c110ff, < bce07e2f37b5e4a427d36fd6b1c14067b27591db	Fixed in bce07e2f37b5e4a427d36fd6b1c14067b27591db
LinuxLinux	Affected ≥ a081c13e39b5c17052a7b46fafa61019c4c110ff, < 79991b770fc3685b1d5cf805b659a879edd19931	Fixed in 79991b770fc3685b1d5cf805b659a879edd19931
LinuxLinux	Affected ≥ a081c13e39b5c17052a7b46fafa61019c4c110ff, < 94e5bdd08e51c450d954bc592f591c233ca5c9df	Fixed in 94e5bdd08e51c450d954bc592f591c233ca5c9df

AI-suggested

The vulnerability description suggests that the fix involves adding a data direction check in the Data-In branch of iscsi_tcp_hdr_dissect(), similar to the existing check in iscsi_tcp_r2t_rsp().

Description

A vulnerability in the Linux kernel's libiscsi_tcp component allows improper handling of Data-In PDUs during WRITE commands. The flaw causes the initiator to write target-supplied data into the caller's own memory pages without verifying the data direction, potentially leading to data corruption. This occurs because the Data-In branch of iscsi_tcp_hdr_dissect() does not check if the command is reading before copying data, unlike the iscsi_tcp_r2t_rsp() function. The issue affects both O_DIRECT and buffered writes, with the latter silently corrupting page cache data.

Impact

The vulnerability can cause data corruption on the initiator side by overwriting the caller's memory pages with data supplied by the target during WRITE commands. This affects both direct I/O (O_DIRECT) and buffered I/O, potentially leading to silent data corruption in the page cache. There is no indication of remote code execution or denial of service from the provided data. No known exploits in the wild have been reported.

Summary

The Linux kernel's libiscsi_tcp module mishandles the data direction check for Data-In PDUs in iscsi_tcp_hdr_dissect(). Specifically, when processing a WRITE command, the function copies the PDU's data segment into the command's scatterlist without verifying if the command is a read operation. This contrasts with iscsi_tcp_r2t_rsp(), which correctly rejects R2T responses for commands not marked as DMA_TO_DEVICE. Consequently, a malicious or misbehaving target can cause the initiator to overwrite its own pinned pages or page cache with target-supplied data, leading to data corruption. The vulnerability was observed with a test target sending a 512-byte Data-In after an R2T for a 128 KB write, resulting in corrupted buffers and page cache without detection.

References

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