CVE Intelligence
Critical

CVE-2026-90414 — In the Linux kernel, the following vulnerability has been resolved: IB/isert: reject…

In the Linux kernel, the following vulnerability has been resolved: IB/isert: reject PDUs declaring more data than was received isert_recv_done() hands each received PDU to the opcode handlers without ever looking at wc->byte_len, the number of bytes the HCA actually placed in the receive descriptor. The handlers then copy that many bytes - the data-segment length the initiator declared in the BHS (ntoh24(hdr->dlength), via the derived unsol_data_len / imm_data_len) - out of the fixed-size descriptor: isert_handle_iscsi_dataout(): sg_copy_from_buffer(sg_start, sg_nents, isert_get_data(rx_desc), unsol_data_len); isert_handle_scsi_cmd(): sg_copy_from_buffer(cmd->se_cmd.t_data_sg, sg_nents, isert_get_data(rx_desc), imm_data_len); Because the declared length is never checked against wc->byte_len, an initiator can declare a data segment larger than the bytes it actually sent (and larger than the descriptor) and cause an out-of-bounds read of the receive buffer. Nothing upstream of isert closes this door: - __iscsit_check_dataout_hdr() bounds the inbound payload against conn_ops->MaxXmitDataSegmentLength (MXDSL) - a transmit parameter, used here for the inbound check. - iscsi_set_connection_parameters() sets ops->MaxXmitDataSegmentLength = ops->TargetRecvDataSegmentLength; and TARGETRECVDATASEGMENTLENGTH is absent from the min()-clamp list in iscsi_check_acceptor_state(), so the value the initiator declares is adopted verbatim (type range 512..16777215). The initiator effectively raises its own ceiling. - isert never clamps the negotiated value to its own fixed receive descriptor (ISER_RX_SIZE, 9216 bytes), so the target core's bound and the descriptor size are unrelated. The imm_data_len == data_len path is more than an over-read: it aliases the receive descriptor via sg_set_buf() and passes it to the backend as the data source for the SCSI WRITE, so an over-declared length causes heap contents past the descriptor to be written through the backend to the backing store. The backend is the victim of the oversized scatterlist isert hands it, not the cause; no read-back of the written bytes was demonstrated. Trigger: after login completes (full feature phase), an initiator that has declared a large TargetRecvDataSegmentLength and a FirstBurstLength that permits unsolicited/immediate data sends a PDU whose declared data-segment length exceeds what was received. With KASAN: BUG: KASAN: slab-out-of-bounds in sg_copy_buffer+0x150/0x1c0 Read of size 4096 at addr ffff888109720800 by task kworker/1:0H/25 Workqueue: ib-comp-wq ib_cq_poll_work Call Trace: sg_copy_buffer+0x150/0x1c0 isert_recv_done+0xba6/0x2390 __ib_process_cq+0xe1/0x390 ib_cq_poll_work+0x46/0x150 isert_recv_done+0xba6 resolves to isert_handle_iscsi_dataout() (ib_isert.c:1160), inlined through isert_rx_opcode(). Validate wc->byte_len against the framing in isert_recv_done() before the PDU reaches any handler, and reinstate the connection if it is short. Because the test compares without subtracting the header length, it also rejects PDUs shorter than the iSER and iSCSI headers, which would otherwise be parsed out of stale descriptor contents. The login handler rejects PDUs shorter than ISER_HEADERS_LEN (commit 29e7b925ae6d ("IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN")) but does not bound the declared length either; that is fixed in the next patch. The data handlers had no length check at all. isert reads the data segment from a fixed offset: isert_get_data() returns the iSER header plus ISER_HEADERS_LEN and makes no adjustment for an AHS. The bytes the handlers touch are therefore exactly [ISER_HEADERS_LEN, ISER_HEADERS_LEN + dlength), and comparing that sum against wc->byte_len bounds precisely the region that is read. An AHS term would only make the test stricter without bounding anything furth ---truncated---

Published Sep 17, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database · CNA: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
—
No EPSS score.
Affects
—
Affected products not yet identified by the sources.
CVSS base
9.1
Critical · 1 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Affected products have not been identified by the sources yet: follow the vendor advisory and map candidate assets by component name.
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Affected products not yet identified by the sources.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.1 CVSS 3.1 Critical 3.9 5.2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Record published
    Oct 15, 2026
  • CVSS changed · 9.1
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Received
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 17, 2026 · 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

Elsewhere on this site

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No FIRST EPSS score.
  • No affected product/version with evidence in the sources.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No CWE classification.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-90414 is "In the Linux kernel, the following vulnerability has been resolved: IB/isert: reject…", rated Critical. Affected products have not been identified by the sources yet. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.1 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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