CVE-2026-52924

Published Jun 24, 2026

Last updated 12 days ago

CVSS critical 9.8

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-52924 describes a use-after-free vulnerability within the Stream Control Transmission Protocol (SCTP) implementation in the Linux kernel. This flaw arises during the handling of a "Stale Cookie ERROR" when an SCTP association is rolled back from the `COOKIE_ECHOED` state to `COOKIE_WAIT`. In this scenario, the `sctp_stream_update()` function frees the old stream table but fails to invalidate `stream->out_curr`, which may still point to a freed `sctp_stream_out` entry. Consequently, later access by SCTP scheduler dequeue paths (such as FCFS, RR, or PRIO) to `stream->out_curr->ext` can lead to a use-after-free condition, as the memory it references has already been released. The resolution involves fully purging the association's outqueue when a Stale Cookie is encountered, ensuring that all pending transmit and retransmit states are dropped and cached pointers are invalidated, thus preventing the use of freed memory.

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.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Secondary
Base score
9.8
Impact score
5.9
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity
CRITICAL

Weaknesses

nvd@nist.gov
CWE-416
134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-416
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
CWE-825

Social media

Hype score
Not currently trending

  1. CVE-2026-52924 https://t.co/asye90XqgU https://t.co/ncmTT7wcXC

    @antonio_taboada

    6 Sept 2026

    46 Impressions

    0 Retweets

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    0 Replies

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  2. Linux-CVE-2026-52924-ubuntu-7.0.0-28 https://t.co/McMiGMHSwk

    @DavidJou734

    5 Sept 2026

    196 Impressions

    0 Retweets

    2 Likes

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  3. CVE-2026-52924: Linux Privilege Escalation. Ubuntu 7.0.0-28 https://t.co/3AHchwz3xC

    @mjadaaan

    5 Sept 2026

    15 Impressions

    0 Retweets

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  4. Exploit disclosed for CVE-2026-52924... 9.8 CVSS Linux Root Privilege Escalation GitHub PoC: https[:]//github[.]com/NebuSec/CyberMeowfia/tree/main/security-research/Linux-CVE-2026-52924-ubuntu-7.0.0-28/ EPSS Lookup: https[:]//epsslookuptool[.]com/?cve=CVE-2026-52924 https://t.c

    @bcs_erictaylor

    4 Sept 2026

    76 Impressions

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  5. Today's exploit is for the latest Ubuntu 26.04, a 9-year-old OOB in SCTP: CVE-2026-52924. It was introduced in Oct 2017 and fixed upstream in Jun 2026. Discovered and exploited by the NebuSec security pipeline. EXP source: https://t.co/3XVCKU1fPL https://t.co/1KwTxvWPju

    @cybermeowfia

    4 Sept 2026

    3297 Impressions

    7 Retweets

    43 Likes

    15 Bookmarks

    0 Replies

    1 Quote

Configurations

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References

Sources include official advisories and independent security research.