CVE-2026-72021 - Vulnerability Details

- ipvs: use parsed transport offset in SCTP state lookup

Description

In the Linux kernel, the following vulnerability has been resolved:

ipvs: use parsed transport offset in SCTP state lookup

set_sctp_state() reads the SCTP chunk header again in order to drive the
IPVS SCTP state table. For IPv6 it computes the offset with
sizeof(struct ipv6hdr), while the surrounding IPVS code uses iph.len from
ip_vs_fill_iph_skb(), where ipv6_find_hdr() has already skipped
extension headers and found the real transport header.

This makes the state machine read from the wrong offset for IPv6 SCTP
packets that carry extension headers. For example, an INIT packet with an
8-byte destination options header can be scheduled correctly by
sctp_conn_schedule(), but set_sctp_state() reads the first byte of the
SCTP verification tag as a DATA chunk type. The connection then moves
from NONE to ESTABLISHED instead of INIT1, gets the longer established
timeout, and updates the active/inactive destination counters
incorrectly. This happens even though the SCTP handshake has not
completed.

Use the parsed transport offset passed down from ip_vs_set_state() for
the SCTP chunk-header lookup. For IPv4 and IPv6 packets without
extension headers this preserves the existing offset.

Published: 2026-08-15

Score: 8.2 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A flaw in the Linux kernel’s IPVS module causes the SCTP state lookup function to use a wrong offset when parsing IPv6 SCTP packets that contain extension headers. As a result, the state machine may interpret part of the SCTP verification tag as a chunk type and transition the connection directly from NONE to ESTABLISHED, bypassing the proper INIT1 state. This premature state transition can lead to incorrect timeout handling, wrong destination counters, and potentially resource exhaustion during the load balancing process.

Affected Systems

The vulnerability exists in the Linux kernel’s IPVS component in all kernel releases before the patch that sets the correct transport offset. Kernel updates that incorporate the commit referenced in the advisory should remediate the issue; exact version boundaries are not specified in the advisory.

Risk and Exploitability

Exploitability requires the ability to send crafted IPv6 SCTP packets with extension headers to a host running IPVS. The attack does not require privileged access, but it can disrupt the load balancer by accelerating connection establishment and skewing traffic distribution. The vulnerability has a CVSS score of 8.2, indicating a high severity, and an EPSS score of < 1%, suggesting a low probability of exploitation. It is not listed in KEV. The likely attack vector is a remote host targeting the IPVS service over the network.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< d2b8b1557ec07ea1bb5dddbceaf4dfe63d388e27
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< 9f94573ab962a9e81954b755da016fa3cd2f5039
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< 290e9e8389b556efc603522e28bd1543846aa336
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< 9cb5ac594ca76d3a71803b23b74c835b0721e628
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< a4a2d2e483d79cc2ad3a170674cf159644acf22b
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< 247d055504dcc852e539b9f7f30d19f9741474bf
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< e5d0bb8871668f20de8f3c94b5ae3f372346bc6e
`2906f66a5682e5670a5eefe991843689b8d8563f`	affected	< 2f75c0faa3361b28e36cc0512b3299e163e25789

Linux

affected

Version	Status	Constraints
`2.6.34`	affected	—
`0`	unaffected	< 2.6.34
`5.10.261`	unaffected	≤ 5.10.*
`5.15.212`	unaffected	≤ 5.15.*
`6.1.178`	unaffected	≤ 6.1.*
`6.6.145`	unaffected	≤ 6.6.*
`6.12.97`	unaffected	≤ 6.12.*
`6.18.40`	unaffected	≤ 6.18.*
`7.1.5`	unaffected	≤ 7.1.*
`7.2`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[2906f66a5682e5670a5eefe991843689b8d8563f,d2b8b1557ec07ea1bb5dddbceaf4dfe63d388e27)`	affected	code_commit	—
`[2906f66a5682e5670a5eefe991843689b8d8563f,9f94573ab962a9e81954b755da016fa3cd2f5039)`	affected	code_commit	—
`[2906f66a5682e5670a5eefe991843689b8d8563f,290e9e8389b556efc603522e28bd1543846aa336)`	affected	code_commit	—
`[2906f66a5682e5670a5eefe991843689b8d8563f,9cb5ac594ca76d3a71803b23b74c835b0721e628)`	affected	code_commit	—
`[2906f66a5682e5670a5eefe991843689b8d8563f,a4a2d2e483d79cc2ad3a170674cf159644acf22b)`	affected	code_commit	—
`[2906f66a5682e5670a5eefe991843689b8d8563f,247d055504dcc852e539b9f7f30d19f9741474bf)`	affected	code_commit	—
`[2906f66a5682e5670a5eefe991843689b8d8563f,e5d0bb8871668f20de8f3c94b5ae3f372346bc6e)`	affected	code_commit	—
`[2906f66a5682e5670a5eefe991843689b8d8563f,2f75c0faa3361b28e36cc0512b3299e163e25789)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`2.6.34`	affected	semver	—
`[0,2.6.34)`	unaffected	semver	—
`[0,5.11.0)`	unaffected	semver	—
`[0,5.16.0)`	unaffected	semver	—
`[0,6.2.0)`	unaffected	semver	—
`[0,6.7.0)`	unaffected	semver	—
`[0,6.13.0)`	unaffected	semver	—
`[0,6.19.0)`	unaffected	semver	—
`[0,7.2.0)`	unaffected	semver	—
`[0,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Update the Linux kernel to the latest stable release that includes the fix for the SCTP state lookup.
If a kernel update cannot be performed immediately, restrict or block IPv6 SCTP traffic with extension headers to the services or disable SCTP support in IPVS.
Monitor IPVS logs for abnormal state transitions and restart the IPVS service if anomalous patterns are observed.

Generated by OpenCVE AI on August 18, 2026 at 05:24 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00589.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/247d055504dcc852e539b9f7f30d19f9741474bf
https://git.kernel.org/stable/c/290e9e8389b556efc603522e28bd1543846aa336
https://git.kernel.org/stable/c/2f75c0faa3361b28e36cc0512b3299e163e25789
https://git.kernel.org/stable/c/9cb5ac594ca76d3a71803b23b74c835b0721e628
https://git.kernel.org/stable/c/9f94573ab962a9e81954b755da016fa3cd2f5039
https://git.kernel.org/stable/c/a4a2d2e483d79cc2ad3a170674cf159644acf22b
https://git.kernel.org/stable/c/d2b8b1557ec07ea1bb5dddbceaf4dfe63d388e27
https://git.kernel.org/stable/c/e5d0bb8871668f20de8f3c94b5ae3f372346bc6e
https://lore.kernel.org/linux-cve-announce/2026081510-CVE-2026-72021-bee2@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-72021
https://www.cve.org/CVERecord?id=CVE-2026-72021

History

Tue, 18 Aug 2026 04:30:00 +0000

Type	Values Removed	Values Added
Weaknesses	CWE-20 CWE-704

Tue, 18 Aug 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-125
References		https://lore.kernel.org/linux-cve-announce/2026081510-CVE-2026-72021-bee2@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-72021 https://www.cve.org/CVERecord?id=CVE-2026-72021
Metrics	threat_severity `None`	threat_severity `Moderate`

Mon, 17 Aug 2026 06:00:00 +0000

Type	Values Removed	Values Added
Metrics		cvssV3_1 `{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'}`

Sat, 15 Aug 2026 08:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-20 CWE-704

Sat, 15 Aug 2026 06:00:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: ipvs: use parsed transport offset in SCTP state lookup set_sctp_state() reads the SCTP chunk header again in order to drive the IPVS SCTP state table. For IPv6 it computes the offset with sizeof(struct ipv6hdr), while the surrounding IPVS code uses iph.len from ip_vs_fill_iph_skb(), where ipv6_find_hdr() has already skipped extension headers and found the real transport header. This makes the state machine read from the wrong offset for IPv6 SCTP packets that carry extension headers. For example, an INIT packet with an 8-byte destination options header can be scheduled correctly by sctp_conn_schedule(), but set_sctp_state() reads the first byte of the SCTP verification tag as a DATA chunk type. The connection then moves from NONE to ESTABLISHED instead of INIT1, gets the longer established timeout, and updates the active/inactive destination counters incorrectly. This happens even though the SCTP handshake has not completed. Use the parsed transport offset passed down from ip_vs_set_state() for the SCTP chunk-header lookup. For IPv4 and IPv6 packets without extension headers this preserves the existing offset.
Title		ipvs: use parsed transport offset in SCTP state lookup
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/247d055504dcc852e539b9f7f30d19f9741474bf https://git.kernel.org/stable/c/290e9e8389b556efc603522e28bd1543846aa336 https://git.kernel.org/stable/c/2f75c0faa3361b28e36cc0512b3299e163e25789 https://git.kernel.org/stable/c/9cb5ac594ca76d3a71803b23b74c835b0721e628 https://git.kernel.org/stable/c/9f94573ab962a9e81954b755da016fa3cd2f5039 https://git.kernel.org/stable/c/a4a2d2e483d79cc2ad3a170674cf159644acf22b https://git.kernel.org/stable/c/d2b8b1557ec07ea1bb5dddbceaf4dfe63d388e27 https://git.kernel.org/stable/c/e5d0bb8871668f20de8f3c94b5ae3f372346bc6e

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-08-15T05:51:47.324Z

Updated: 2026-08-17T05:39:31.586Z

Reserved: 2026-08-09T03:40:39.900Z

Link: CVE-2026-72021

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-08-15T06:21:01.053

Modified: 2026-08-17T06:17:59.710

Link: CVE-2026-72021

Redhat

Severity : Moderate

Publid Date: 2026-08-15T00:00:00Z

Links: CVE-2026-72021 - Bugzilla

OpenCVE Enrichment

Updated: 2026-08-18T05:30:08Z

Weaknesses

CWE-125
Out-of-bounds Read

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact High

User Interaction None

Subscriptions

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