CVE-2021-46999
Linux Kernel use-after-free
- Published28 Feb 2024
Description
In the Linux kernel, the following vulnerability has been resolved: sctp: do asoc update earlier in sctp_sf_do_dupcook_a There's a panic that occurs in a few of envs, the call trace is as below: [] general protection fault, ... 0x29acd70f1000a: 0000 [#1] SMP PTI [] RIP: 0010:sctp_ulpevent_notify_peer_addr_change+0x4b/0x1fa [sctp] [] sctp_assoc_control_transport+0x1b9/0x210 [sctp] [] sctp_do_8_2_transport_strike.isra.16+0x15c/0x220 [sctp] [] sctp_cmd_interpreter.isra.21+0x1231/0x1a10 [sctp] [] sctp_do_sm+0xc3/0x2a0 [sctp] [] sctp_generate_timeout_event+0x81/0xf0 [sctp] This is caused by a transport use-after-free issue. When processing a duplicate COOKIE-ECHO chunk in sctp_sf_do_dupcook_a(), both COOKIE-ACK and SHUTDOWN chunks are allocated with the transort from the new asoc. However, later in the sideeffect machine, the old asoc is used to send them out and old asoc's shutdown_last_sent_to is set to the transport that SHUTDOWN chunk attached to in sctp_cmd_setup_t2(), which actually belongs to the new asoc. After the new_asoc is freed and the old asoc T2 timeout, the old asoc's shutdown_last_sent_to that is already freed would be accessed in sctp_sf_t2_timer_expire(). Thanks Alexander and Jere for helping dig into this issue. To fix it, this patch is to do the asoc update first, then allocate the COOKIE-ACK and SHUTDOWN chunks with the 'updated' old asoc. This would make more sense, as a chunk from an asoc shouldn't be sent out with another asoc. We had fixed quite a few issues caused by this.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/0bfd913c2121b3d553bfd52810fe6061d542d625
- https://git.kernel.org/stable/c/35b4f24415c854cd718ccdf38dbea6297f010aae
- https://git.kernel.org/stable/c/61b877bad9bb0d82b7d8841be50872557090a704
- https://git.kernel.org/stable/c/b1b31948c0af44628e43353828453461bb74098f
- https://git.kernel.org/stable/c/d624f2991b977821375fbd56c91b0c91d456a697
- https://git.kernel.org/stable/c/f01988ecf3654f805282dce2d3bb9afe68d2691e
References
- https://git.kernel.org/stable/c/0bfd913c2121b3d553bfd52810fe6061d542d625
- https://git.kernel.org/stable/c/35b4f24415c854cd718ccdf38dbea6297f010aae
- https://git.kernel.org/stable/c/61b877bad9bb0d82b7d8841be50872557090a704
- https://git.kernel.org/stable/c/b1b31948c0af44628e43353828453461bb74098f
- https://git.kernel.org/stable/c/d624f2991b977821375fbd56c91b0c91d456a697
- https://git.kernel.org/stable/c/f01988ecf3654f805282dce2d3bb9afe68d2691e
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2021-46999 being actively exploited?
CVE-2021-46999 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.74%.
How severe is CVE-2021-46999?
CVE-2021-46999 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.74% probability of exploitation.
Which products are affected by CVE-2021-46999?
Affected products include Linux Kernel.
How do I fix CVE-2021-46999?
Upgrade affected software to a fixed version, for example Linux Kernel 4.19.191 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2021-46999 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.