Bug 2492095 (CVE-2026-52924)
| Summary: | CVE-2026-52924 kernel: sctp: purge outqueue on stale COOKIE-ECHO handling | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | akito5623, rhel-process-autobot, watson-tool-maintainers |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation. This vulnerability, a use-after-free, occurs when the system processes a Stale Cookie ERROR during the setup or reconfiguration of an SCTP association. A remote attacker could exploit this by sending specially crafted SCTP packets. This could lead to a system crash, causing a Denial of Service (DoS).
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2026062431-CVE-2026-52924-9f0b@gregkh/T This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:59737 https://access.redhat.com/errata/RHSA-2026:59737 This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:59723 https://access.redhat.com/errata/RHSA-2026:59723 This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:59821 https://access.redhat.com/errata/RHSA-2026:59821 Public exploit/PoC code for CVE-2026-52924 has been released. Red Hat CVE: https://access.redhat.com/security/cve/cve-2026-52924 Public exploit/PoC: Ubuntu 7.0.0-28: https://github.com/NebuSec/CyberMeowfia/tree/main/security-research/Linux-CVE-2026-52924-ubuntu-7.0.0-28 Arch Linux 6.19.10: https://github.com/NebuSec/CyberMeowfia/tree/main/security-research/Linux-CVE-2026-52924-Arch-6.19.10 A demonstration video has also been published: https://x.com/cybermeowfia/status/2095706087064527011 Possible fix for RHEL 10 (Linux 6.12.94 stable backport): https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1d4652f677906a64487c13f9ace54b0eb263b5d0 Possible mitigation for systems that do not require SCTP: echo "install sctp /bin/true" > /etc/modprobe.d/disable-sctp.conf This mitigation disables the SCTP kernel module and should only be used on systems where SCTP is not required. Please review the affected RHEL releases and current impact assessment in light of the publicly available exploit/PoC and demonstration video. This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:67471 https://access.redhat.com/errata/RHSA-2026:67471 This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Via RHSA-2026:73645 https://access.redhat.com/errata/RHSA-2026:73645 This issue has been addressed in the following products: Red Hat Enterprise Linux 9.6 Extended Update Support Via RHSA-2026:74174 https://access.redhat.com/errata/RHSA-2026:74174 This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:77214 https://access.redhat.com/errata/RHSA-2026:77214 This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On Via RHSA-2026:77216 https://access.redhat.com/errata/RHSA-2026:77216 This issue has been addressed in the following products: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Via RHSA-2026:77217 https://access.redhat.com/errata/RHSA-2026:77217 This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:77215 https://access.redhat.com/errata/RHSA-2026:77215 This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2026:77301 https://access.redhat.com/errata/RHSA-2026:77301 This issue has been addressed in the following products: Red Hat Enterprise Linux 10.0 Extended Update Support Via RHSA-2026:77634 https://access.redhat.com/errata/RHSA-2026:77634 |
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.