VulnerabilityPublished 25 Jul 2026

CVE-2026-64268: Linux kernel · RDMA/siw: bound Read Response placement to the RREAD length

Source GCVE Database

Authoritative record:CVE-2026-64268· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in b2e26c955f8dd7e8d3f16c858db05245ea4fa817 : 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: 0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in b2e26c955f8dd7e8d3f16c858db05245ea4fa817, a31b6d18ded3cc32d9ee85a6ff0726d4274887b2, 595e6537ad1a210da32cbb9a7f91aa73090915ba +5

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 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.

ghsa-86rp-m36j-7r28

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < b2e26c955f8dd7e8d3f16c858db05245ea4fa817	Fixed in b2e26c955f8dd7e8d3f16c858db05245ea4fa817
LinuxLinux	Affected ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < a31b6d18ded3cc32d9ee85a6ff0726d4274887b2	Fixed in a31b6d18ded3cc32d9ee85a6ff0726d4274887b2
LinuxLinux	Affected ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 595e6537ad1a210da32cbb9a7f91aa73090915ba	Fixed in 595e6537ad1a210da32cbb9a7f91aa73090915ba
LinuxLinux	Affected ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 423a78ff7928c2601013f73ec6d896f5597d0df5	Fixed in 423a78ff7928c2601013f73ec6d896f5597d0df5
LinuxLinux	Affected ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 75c93cd3c421890f49ea93f0b978b9b7bb10e5e3	Fixed in 75c93cd3c421890f49ea93f0b978b9b7bb10e5e3
LinuxLinux	Affected ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 7d29f7e9dbd844cae4d3e559cf78324b9642fd6b	Fixed in 7d29f7e9dbd844cae4d3e559cf78324b9642fd6b

AI-suggested

A fix is available that bounds each Read Response segment before placement and terminates connections that would cause buffer overruns. Users should apply the official Linux kernel patches that address this vulnerability.

Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/siw: bound Read Response placement to the RREAD length In drivers/infiniband/sw/siw/siw_qp_rx.c, siw_proc_rresp() places each inbound Read Response DDP segment at sge->laddr + wqe->processed and then accumulates wqe->processed, but it never checks the running total against the sink buffer length on continuation segments. siw_check_sge() resolves and validates the sink memory only on the first fragment (the if (!*mem) branch), and siw_rresp_check_ntoh() compares the cumulative length against wqe->bytes only on the final segment (the !frx->more_ddp_segs guard). A connected siw peer that answers an outstanding RREAD with Read Response segments that keep the DDP Last flag clear, carrying more total payload than the RREAD requested, drives wqe->processed past the validated sink buffer; the next siw_rx_data() call writes out of bounds at sge->laddr + wqe->processed. siw runs iWARP over ordinary routable TCP, so the peer is the remote end of an established RDMA connection and needs no local privilege. Bound every segment before placement, exactly as siw_proc_send() and siw_proc_write() already do for their tagged and untagged paths, and terminate the connection with a base-or-bounds DDP error when the Read Response would overrun the sink buffer. This is the second receive-path length fix for this file. A separate change rejects an MPA FPDU length that underflows the per-fragment remainder in the header decode; that guard does not cover this case, because here each individual segment length is self-consistent and only the accumulated placement offset overruns the buffer.

Impact

A remote attacker with an established RDMA connection can cause out-of-bounds memory writes in kernel space by sending malicious Read Response segments that exceed the requested length. This could lead to memory corruption, potential kernel crashes, or other undefined behavior. No local privileges are required, but the attacker must be a connected RDMA peer.

Summary

The Linux kernel's siw RDMA driver (infiniband/sw/siw/siw_qp_rx.c) improperly handles the placement of inbound Read Response DDP segments by accumulating processed lengths without verifying the total against the sink buffer length on continuation segments. While initial fragment validation occurs, subsequent segments can cause wqe->processed to exceed the validated buffer size, resulting in out-of-bounds writes at sge->laddr + wqe->processed. This vulnerability can be triggered by a remote connected siw peer over an established RDMA connection without requiring local privileges. The fix involves bounding every segment before placement and terminating the connection with a DDP error if an overrun would occur.

References

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