{"id":"CVE-2021-46999","state":"PUBLISHED","title":"sctp: do asoc update earlier in sctp_sf_do_dupcook_a","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: do asoc update earlier in sctp_sf_do_dupcook_a\n\nThere's a panic that occurs in a few of envs, the call trace is as below:\n\n  [] general protection fault, ... 0x29acd70f1000a: 0000 [#1] SMP PTI\n  [] RIP: 0010:sctp_ulpevent_notify_peer_addr_change+0x4b/0x1fa [sctp]\n  []  sctp_assoc_control_transport+0x1b9/0x210 [sctp]\n  []  sctp_do_8_2_transport_strike.isra.16+0x15c/0x220 [sctp]\n  []  sctp_cmd_interpreter.isra.21+0x1231/0x1a10 [sctp]\n  []  sctp_do_sm+0xc3/0x2a0 [sctp]\n  []  sctp_generate_timeout_event+0x81/0xf0 [sctp]\n\nThis is caused by a transport use-after-free issue. When processing a\nduplicate COOKIE-ECHO chunk in sctp_sf_do_dupcook_a(), both COOKIE-ACK\nand SHUTDOWN chunks are allocated with the transort from the new asoc.\nHowever, later in the sideeffect machine, the old asoc is used to send\nthem out and old asoc's shutdown_last_sent_to is set to the transport\nthat SHUTDOWN chunk attached to in sctp_cmd_setup_t2(), which actually\nbelongs to the new asoc. After the new_asoc is freed and the old asoc\nT2 timeout, the old asoc's shutdown_last_sent_to that is already freed\nwould be accessed in sctp_sf_t2_timer_expire().\n\nThanks Alexander and Jere for helping dig into this issue.\n\nTo fix it, this patch is to do the asoc update first, then allocate\nthe COOKIE-ACK and SHUTDOWN chunks with the 'updated' old asoc. This\nwould make more sense, as a chunk from an asoc shouldn't be sent out\nwith another asoc. We had fixed quite a few issues caused by this.","publishedAt":"2024-02-28T08:13:22.256Z","updatedAt":"2026-08-05T08:45:28.974Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"db8bf823e70f239372c62f13e4eb6f08a1665e8c","status":"affected","lessThan":"d624f2991b977821375fbd56c91b0c91d456a697","versionType":"git"},{"version":"a204d577be70e0a0a6023cf1b9859c9ebffaeecd","status":"affected","lessThan":"b1b31948c0af44628e43353828453461bb74098f","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"f01988ecf3654f805282dce2d3bb9afe68d2691e","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"61b877bad9bb0d82b7d8841be50872557090a704","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"0bfd913c2121b3d553bfd52810fe6061d542d625","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"35b4f24415c854cd718ccdf38dbea6297f010aae","versionType":"git"},{"version":"a5ce8531ea508d270822b2bc6140c6198c8a2a7b","status":"affected","versionType":"git"},{"version":"4.19.123","status":"affected","lessThan":"4.19.191","versionType":"semver"},{"version":"5.4.41","status":"affected","lessThan":"5.4.120","versionType":"semver"},{"version":"5.6.13","status":"affected","lessThan":"5.7","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/sm_statefuns.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"4.19.191","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.120","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.38","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.11.22","status":"unaffected","lessThanOrEqual":"5.11.*","versionType":"semver"},{"version":"5.12.5","status":"unaffected","lessThanOrEqual":"5.12.*","versionType":"semver"},{"version":"5.13","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/sm_statefuns.c"]}],"references":["https://git.kernel.org/stable/c/d624f2991b977821375fbd56c91b0c91d456a697","https://git.kernel.org/stable/c/b1b31948c0af44628e43353828453461bb74098f","https://git.kernel.org/stable/c/f01988ecf3654f805282dce2d3bb9afe68d2691e","https://git.kernel.org/stable/c/61b877bad9bb0d82b7d8841be50872557090a704","https://git.kernel.org/stable/c/0bfd913c2121b3d553bfd52810fe6061d542d625","https://git.kernel.org/stable/c/35b4f24415c854cd718ccdf38dbea6297f010aae"],"weaknesses":[],"ingestedAt":"2026-10-29T19:49:16.371Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/46xxx/CVE-2021-46999.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-46999","state":"PUBLISHED","datePublished":"2024-02-28T08:13:22.256Z","dateUpdated":"2026-08-05T08:45:28.974Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-02-27T18:42:55.950Z"},"containers":{"cna":{"title":"sctp: do asoc update earlier in sctp_sf_do_dupcook_a","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: do asoc update earlier in sctp_sf_do_dupcook_a\n\nThere's a panic that occurs in a few of envs, the call trace is as below:\n\n  [] general protection fault, ... 0x29acd70f1000a: 0000 [#1] SMP PTI\n  [] RIP: 0010:sctp_ulpevent_notify_peer_addr_change+0x4b/0x1fa [sctp]\n  []  sctp_assoc_control_transport+0x1b9/0x210 [sctp]\n  []  sctp_do_8_2_transport_strike.isra.16+0x15c/0x220 [sctp]\n  []  sctp_cmd_interpreter.isra.21+0x1231/0x1a10 [sctp]\n  []  sctp_do_sm+0xc3/0x2a0 [sctp]\n  []  sctp_generate_timeout_event+0x81/0xf0 [sctp]\n\nThis is caused by a transport use-after-free issue. When processing a\nduplicate COOKIE-ECHO chunk in sctp_sf_do_dupcook_a(), both COOKIE-ACK\nand SHUTDOWN chunks are allocated with the transort from the new asoc.\nHowever, later in the sideeffect machine, the old asoc is used to send\nthem out and old asoc's shutdown_last_sent_to is set to the transport\nthat SHUTDOWN chunk attached to in sctp_cmd_setup_t2(), which actually\nbelongs to the new asoc. After the new_asoc is freed and the old asoc\nT2 timeout, the old asoc's shutdown_last_sent_to that is already freed\nwould be accessed in sctp_sf_t2_timer_expire().\n\nThanks Alexander and Jere for helping dig into this issue.\n\nTo fix it, this patch is to do the asoc update first, then allocate\nthe COOKIE-ACK and SHUTDOWN chunks with the 'updated' old asoc. This\nwould make more sense, as a chunk from an asoc shouldn't be sent out\nwith another asoc. We had fixed quite a few issues caused by this."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"db8bf823e70f239372c62f13e4eb6f08a1665e8c","status":"affected","lessThan":"d624f2991b977821375fbd56c91b0c91d456a697","versionType":"git"},{"version":"a204d577be70e0a0a6023cf1b9859c9ebffaeecd","status":"affected","lessThan":"b1b31948c0af44628e43353828453461bb74098f","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"f01988ecf3654f805282dce2d3bb9afe68d2691e","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"61b877bad9bb0d82b7d8841be50872557090a704","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"0bfd913c2121b3d553bfd52810fe6061d542d625","versionType":"git"},{"version":"145cb2f7177d94bc54563ed26027e952ee0ae03c","status":"affected","lessThan":"35b4f24415c854cd718ccdf38dbea6297f010aae","versionType":"git"},{"version":"a5ce8531ea508d270822b2bc6140c6198c8a2a7b","status":"affected","versionType":"git"},{"version":"4.19.123","status":"affected","lessThan":"4.19.191","versionType":"semver"},{"version":"5.4.41","status":"affected","lessThan":"5.4.120","versionType":"semver"},{"version":"5.6.13","status":"affected","lessThan":"5.7","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/sm_statefuns.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"4.19.191","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.120","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.38","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.11.22","status":"unaffected","lessThanOrEqual":"5.11.*","versionType":"semver"},{"version":"5.12.5","status":"unaffected","lessThanOrEqual":"5.12.*","versionType":"semver"},{"version":"5.13","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/sm_statefuns.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/d624f2991b977821375fbd56c91b0c91d456a697"},{"url":"https://git.kernel.org/stable/c/b1b31948c0af44628e43353828453461bb74098f"},{"url":"https://git.kernel.org/stable/c/f01988ecf3654f805282dce2d3bb9afe68d2691e"},{"url":"https://git.kernel.org/stable/c/61b877bad9bb0d82b7d8841be50872557090a704"},{"url":"https://git.kernel.org/stable/c/0bfd913c2121b3d553bfd52810fe6061d542d625"},{"url":"https://git.kernel.org/stable/c/35b4f24415c854cd718ccdf38dbea6297f010aae"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The bug is in SCTP COOKIE-ECHO processing on the packet receive path (sctp_rcv → sctp_sf_do_5_2_4_dupcook → sctp_sf_do_dupcook_a); a remote peer triggers it by sending SCTP packets over IP.\nAC:L - A peer can observe SHUTDOWN, withhold SHUTDOWN-ACK to keep the victim in SHUTDOWN_SENT, then complete a restart INIT/COOKIE-ECHO exchange; the attacker controls both the timing and the packets that create the UAF.\nPR:N - No local privileges are required—any remote SCTP client that completes a normal association handshake can send the restart COOKIE-ECHO; cookie HMAC is protocol anti-DoS, not OS authentication.\nUI:N - Exploitation requires only attacker-sent SCTP packets; no victim user action beyond ordinary association close is needed.\nS:U - Impact stays within the vulnerable host kernel (transport UAF / privilege escalation or crash); it does not cross a VM, IOMMU, or other security boundary.\nC:H - This is a heap use-after-free of an sctp_transport; freed object reuse can yield arbitrary kernel read primitives.\nI:H - The same transport UAF enables heap spraying and write/control-flow hijacking primitives for integrity compromise or code execution.\nA:H - The bug causes a reproducible kernel general protection fault / panic when the T2 timer later dereferences the freed transport."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T08:45:28.974Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.123","versionEndExcluding":"4.19.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.41","versionEndExcluding":"5.4.120"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.10.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.11.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.12.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.6.13"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-06-21T16:28:23.491999Z","id":"CVE-2021-46999","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-06-21T16:28:34.904Z"}},{"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/d624f2991b977821375fbd56c91b0c91d456a697","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/b1b31948c0af44628e43353828453461bb74098f","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/f01988ecf3654f805282dce2d3bb9afe68d2691e","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/61b877bad9bb0d82b7d8841be50872557090a704","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/0bfd913c2121b3d553bfd52810fe6061d542d625","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/35b4f24415c854cd718ccdf38dbea6297f010aae","tags":["x_transferred"]}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2024-08-04T05:24:37.916Z"}}]}}}