CVE-2026-52924 - Vulnerability Details

- sctp: purge outqueue on stale COOKIE-ECHO handling

Description

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

sctp: purge outqueue on stale COOKIE-ECHO handling

sctp_stream_update() is only invoked when the association is moved into
COOKIE_WAIT during association setup/reconfiguration. In this path, the
outbound stream scheduler state (stream->out_curr) is expected to be
clean, since no user data should have been transmitted yet unless the
state machine has already partially progressed.

However, a corner case exists in sctp_sf_do_5_2_6_stale(): when a
Stale Cookie ERROR is received, the association is rolled back from
COOKIE_ECHOED to COOKIE_WAIT. In this scenario, user data may already
have been queued and even bundled with the COOKIE-ECHO chunk.

During the rollback, sctp_stream_update() frees the old stream table
and installs a new one, but it does not invalidate stream->out_curr.
As a result, out_curr may still point to a freed sctp_stream_out
entry from the previous stream state.

Later, SCTP scheduler dequeue paths (FCFS, RR, PRIO, etc.) rely on
stream->out_curr->ext, which can lead to use-after-free once the old
stream state has been released via sctp_stream_free().

This results in crashes such as (reported by Yuqi):

BUG: KASAN: slab-use-after-free in sctp_sched_fcfs_dequeue+0x13a/0x140
Read of size 8 at addr ff1100004d4d3208 by task mini_poc/9312
CPU: 1 UID: 1001 PID: 9312 Comm: mini_poc Not tainted
7.1.0-rc1-00305-gbd3a4795d574 #5 PREEMPT(full)
sctp_sched_fcfs_dequeue+0x13a/0x140
sctp_outq_flush+0x1603/0x33e0
sctp_do_sm+0x31c9/0x5d30
sctp_assoc_bh_rcv+0x392/0x6f0
sctp_inq_push+0x1db/0x270
sctp_rcv+0x138d/0x3c10

Fix this by fully purging the association outqueue when handling the
Stale Cookie case. This ensures all pending transmit and retransmit
state is dropped, and any scheduler cached pointers are invalidated,
making it safe to rebuild stream state during COOKIE_WAIT restart.

Updating only stream->out_curr would be insufficient, since queued
and retransmittable data would still reference the old stream state and
trigger later use-after-free in dequeue paths.

Published: 2026-06-24

Score: 9.8 Critical

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The Linux kernel SCTP implementation contains a flaw where, during rollback from a stale cookie error, a pointer to a freed stream structure is retained, allowing the scheduler’s dequeue paths to dereference freed memory and trigger a kernel crash‑after‑free condition and can bring the affected system down if the vulnerability is exercised.

Affected Systems

The defect exists in all Linux kernel versions that ship the SCTP stack and have not applied the patch contained in the commit set referenced in the CVE. Because the Linux kernel is widely distributed across many Linux distributions, every system running an unpatched kernel with SCTP enabled is potentially affected.

Risk and Exploitability

The CVSS score of 9.8 indicates severe impact, while the EPSS score of <1% indicates a very low probability that the vulnerability will be explored and exploited in the wild. The flaw is not listed as a known exploited vulnerability by CISA. Based on how SCTP operates, it is reasonable to infer that an attacker could trigger the crash by sending malicious SCTP packets over the network, thereby exploiting the stale cookie path; however, the CVE data does not provide a published exploit and the actual exploitation path remains unverified.

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
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< 84b7a319105db2f917ccdcf502bdc866082b1285
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< f46e1d1a758878f0d22c4fbbd1bf42bb7165d1e8
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< 3c0741a441a7df7099d7ca6a64a6a0de09c677c8
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< 2afc9e684dc7fecf73db1edc937ebbc47b4b68dc
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< 1d4652f677906a64487c13f9ace54b0eb263b5d0
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< a6207349e703cfc04756a4d16dec9176135813a5
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< 83ade59e5da365f4bf8bce72c5a38774202b442f
`5bbbbe32a43199c2b9ea5ea66fab6241c64beb51`	affected	< e374b22e9b07b72a25909621464ff74096151bfb

Linux

affected

Version	Status	Constraints
`4.15`	affected	—
`0`	unaffected	< 4.15
`5.10.259`	unaffected	≤ 5.10.*
`5.15.210`	unaffected	≤ 5.15.*
`6.1.176`	unaffected	≤ 6.1.*
`6.6.143`	unaffected	≤ 6.6.*
`6.12.94`	unaffected	≤ 6.12.*
`6.18.36`	unaffected	≤ 6.18.*
`7.0.13`	unaffected	≤ 7.0.*
`7.1`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,84b7a319105db2f917ccdcf502bdc866082b1285)`	affected	code_commit	—
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,f46e1d1a758878f0d22c4fbbd1bf42bb7165d1e8)`	affected	code_commit	—
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,3c0741a441a7df7099d7ca6a64a6a0de09c677c8)`	affected	code_commit	—
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,2afc9e684dc7fecf73db1edc937ebbc47b4b68dc)`	affected	code_commit	—
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,1d4652f677906a64487c13f9ace54b0eb263b5d0)`	affected	code_commit	—
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,a6207349e703cfc04756a4d16dec9176135813a5)`	affected	code_commit	—
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,83ade59e5da365f4bf8bce72c5a38774202b442f)`	affected	code_commit	—
`[5bbbbe32a43199c2b9ea5ea66fab6241c64beb51,e374b22e9b07b72a25909621464ff74096151bfb)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`4.15`	affected	generic	—
`[0,4.15)`	unaffected	semver	—
`[5.10.259,5.11.0)`	unaffected	semver	—
`[5.15.210,5.16.0)`	unaffected	semver	—
`[6.1.176,6.2.0)`	unaffected	semver	—
`[6.6.143,6.7.0)`	unaffected	semver	—
`[6.12.94,6.13.0)`	unaffected	semver	—
`[6.18.36,6.19.0)`	unaffected	semver	—
`[7.0.13,7.1.0)`	unaffected	semver	—
`[7.1,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Apply a kernel update that includes the SCTP use‑after‑free fix, as detailed in the commit references attached to the CVE.
If a patch cannot be applied immediately, disable SCTP networking at the system level (e.g., by setting net.sctp.enable=0 via sysctl or compiling the kernel with CONFIG_SCTP=n).
Continuously monitor kernel logs for KASAN or Oops messages related to SCTP and ensure that any vendor‑issued advisories are promptly addressed.

Generated by OpenCVE AI on June 28, 2026 at 14:50 UTC.

Tracking

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Advisories

Source	ID	Title
Debian DLA	DLA-4664-1	linux security update
Debian DLA	DLA-4665-1	linux security update
Debian DLA	DLA-4671-1	linux-6.1 security update

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

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 0.00335.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/1d4652f677906a64487c13f9ace54b0eb263b5d0
https://git.kernel.org/stable/c/2afc9e684dc7fecf73db1edc937ebbc47b4b68dc
https://git.kernel.org/stable/c/3c0741a441a7df7099d7ca6a64a6a0de09c677c8
https://git.kernel.org/stable/c/83ade59e5da365f4bf8bce72c5a38774202b442f
https://git.kernel.org/stable/c/84b7a319105db2f917ccdcf502bdc866082b1285
https://git.kernel.org/stable/c/a6207349e703cfc04756a4d16dec9176135813a5
https://git.kernel.org/stable/c/e374b22e9b07b72a25909621464ff74096151bfb
https://git.kernel.org/stable/c/f46e1d1a758878f0d22c4fbbd1bf42bb7165d1e8
https://lore.kernel.org/linux-cve-announce/2026062431-CVE-2026-52924-9f0b@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-52924
https://www.cve.org/CVERecord?id=CVE-2026-52924

History

Sun, 28 Jun 2026 11:15:00 +0000

Type	Values Removed	Values Added
Weaknesses	CWE-416

Sun, 28 Jun 2026 08:00:00 +0000

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}`	cvssV3_1 `{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}`

Thu, 25 Jun 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-825
References		https://lore.kernel.org/linux-cve-announce/2026062431-CVE-2026-52924-9f0b@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-52924 https://www.cve.org/CVERecord?id=CVE-2026-52924
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}` threat_severity `Important`

Wed, 24 Jun 2026 13:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-416

Wed, 24 Jun 2026 07:45:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: sctp: purge outqueue on stale COOKIE-ECHO handling sctp_stream_update() is only invoked when the association is moved into COOKIE_WAIT during association setup/reconfiguration. In this path, the outbound stream scheduler state (stream->out_curr) is expected to be clean, since no user data should have been transmitted yet unless the state machine has already partially progressed. However, a corner case exists in sctp_sf_do_5_2_6_stale(): when a Stale Cookie ERROR is received, the association is rolled back from COOKIE_ECHOED to COOKIE_WAIT. In this scenario, user data may already have been queued and even bundled with the COOKIE-ECHO chunk. During the rollback, sctp_stream_update() frees the old stream table and installs a new one, but it does not invalidate stream->out_curr. As a result, out_curr may still point to a freed sctp_stream_out entry from the previous stream state. Later, SCTP scheduler dequeue paths (FCFS, RR, PRIO, etc.) rely on stream->out_curr->ext, which can lead to use-after-free once the old stream state has been released via sctp_stream_free(). This results in crashes such as (reported by Yuqi): BUG: KASAN: slab-use-after-free in sctp_sched_fcfs_dequeue+0x13a/0x140 Read of size 8 at addr ff1100004d4d3208 by task mini_poc/9312 CPU: 1 UID: 1001 PID: 9312 Comm: mini_poc Not tainted 7.1.0-rc1-00305-gbd3a4795d574 #5 PREEMPT(full) sctp_sched_fcfs_dequeue+0x13a/0x140 sctp_outq_flush+0x1603/0x33e0 sctp_do_sm+0x31c9/0x5d30 sctp_assoc_bh_rcv+0x392/0x6f0 sctp_inq_push+0x1db/0x270 sctp_rcv+0x138d/0x3c10 Fix this by fully purging the association outqueue when handling the Stale Cookie case. This ensures all pending transmit and retransmit state is dropped, and any scheduler cached pointers are invalidated, making it safe to rebuild stream state during COOKIE_WAIT restart. Updating only stream->out_curr would be insufficient, since queued and retransmittable data would still reference the old stream state and trigger later use-after-free in dequeue paths.
Title		sctp: purge outqueue on stale COOKIE-ECHO handling
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/1d4652f677906a64487c13f9ace54b0eb263b5d0 https://git.kernel.org/stable/c/2afc9e684dc7fecf73db1edc937ebbc47b4b68dc https://git.kernel.org/stable/c/3c0741a441a7df7099d7ca6a64a6a0de09c677c8 https://git.kernel.org/stable/c/83ade59e5da365f4bf8bce72c5a38774202b442f https://git.kernel.org/stable/c/84b7a319105db2f917ccdcf502bdc866082b1285 https://git.kernel.org/stable/c/a6207349e703cfc04756a4d16dec9176135813a5 https://git.kernel.org/stable/c/e374b22e9b07b72a25909621464ff74096151bfb https://git.kernel.org/stable/c/f46e1d1a758878f0d22c4fbbd1bf42bb7165d1e8

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-06-24T07:14:18.646Z

Updated: 2026-07-13T12:05:26.393Z

Reserved: 2026-06-09T07:44:35.368Z

Link: CVE-2026-52924

Vulnrichment

No data.

NVD

No data.

Redhat

Severity : Important

Publid Date: 2026-06-24T00:00:00Z

Links: CVE-2026-52924 - Bugzilla

OpenCVE Enrichment

Updated: 2026-06-28T15:00:12Z

Weaknesses

CWE-825
Expired Pointer Dereference

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

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