{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-41007", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-07-12T12:17:45.610Z", "datePublished": "2024-07-15T08:48:10.174Z", "dateUpdated": "2026-08-05T11:34:33.523Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:34:33.523Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: avoid too many retransmit packets\n\nIf a TCP socket is using TCP_USER_TIMEOUT, and the other peer\nretracted its window to zero, tcp_retransmit_timer() can\nretransmit a packet every two jiffies (2 ms for HZ=1000),\nfor about 4 minutes after TCP_USER_TIMEOUT has 'expired'.\n\nThe fix is to make sure tcp_rtx_probe0_timed_out() takes\nicsk->icsk_user_timeout into account.\n\nBefore blamed commit, the socket would not timeout after\nicsk->icsk_user_timeout, but would use standard exponential\nbackoff for the retransmits.\n\nAlso worth noting that before commit e89688e3e978 (\"net: tcp:\nfix unexcepted socket die when snd_wnd is 0\"), the issue\nwould last 2 minutes instead of 4." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bug is in the core TCP stack (net/ipv4/tcp_timer.c) and is driven entirely by a remote peer's advertised window and ACKs; no local access is needed. Any remote TCP peer of a socket with TCP_USER_TIMEOUT set (NFS client transports, ocfs2, BPF-sockops-configured connections, gRPC/Envoy/HAProxy/Redis servers) can trigger it.\nAC:L - The attacker fully controls the trigger — shrink the receive window to zero (stop reading, or use a custom stack) and keep ACKing the zero-window probes to keep tp->rcv_tstamp fresh so tcp_rtx_probe0_timed_out() never aborts. No race, timing luck, or memory-layout dependency; TCP_USER_TIMEOUT being set is a common attacker-independent deployment property (sunrpc sets it unconditionally), i.e. part of the vulnerable configuration.\nPR:N - No authentication or credentials are required — establishing a TCP connection and getting unacked data in flight (e.g. a banner or a pre-auth response) is sufficient. Locally the same condition is reachable by any unprivileged user via setsockopt(TCP_USER_TIMEOUT), which has no capability check.\nUI:N - The packet storm is generated autonomously by the kernel retransmit timer once the peer advertises a zero window. No action by any local user or administrator is needed.\nS:U - The CPU, softirq and network-bandwidth exhaustion stay within the affected host's own security authority. No privilege or virtualization boundary is crossed.\nC:N - The bug only causes excessive retransmission of data already queued for and destined to that same peer — no out-of-bounds read, uninitialized memory, or kernel-pointer exposure. The only extra output is an already-existing net_dbg_ratelimited() message.\nI:N - There is no memory corruption, out-of-bounds write, or type confusion; the emitted packets are legitimate, correctly-formed retransmissions. No kernel or user data is modified.\nA:H - tcp_clamp_rto_to_user_timeout() pins the retransmit timer to 1 jiffy, producing 500–1000 packets/sec per socket, each with a tcp_enter_loss() and a __sk_dst_reset() route lookup, and a peer that keeps ACKing probes makes this unbounded in time rather than the 4 minutes noted in the changelog. Scaled across many connections this is a sustained, unauthenticated CPU and link-saturation denial of service, and the socket also silently ignores the TCP_USER_TIMEOUT the application relies on for failure detection." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/tcp_timer.c" ], "versions": [ { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "7bb7670f92bfbd05fc41a8f9a8f358b7ffed65f4", "status": "affected", "versionType": "git" }, { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "d2346fca5bed130dc712f276ac63450201d52969", "status": "affected", "versionType": "git" }, { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "5d7e64d70a11d988553a08239c810a658e841982", "status": "affected", "versionType": "git" }, { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "04317a2471c2f637b4c49cbd0e9c0d04a519f570", "status": "affected", "versionType": "git" }, { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "e113cddefa27bbf5a79f72387b8fbd432a61a466", "status": "affected", "versionType": "git" }, { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "dfcdd7f89e401d2c6616be90c76c2fac3fa98fde", "status": "affected", "versionType": "git" }, { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "66cb64a1d2239cd0309f9b5038b05462570a5be1", "status": "affected", "versionType": "git" }, { "version": "b701a99e431db784714c32fc6b68123045714679", "lessThan": "97a9063518f198ec0adb2ecb89789de342bb8283", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/tcp_timer.c" ], "versions": [ { "version": "4.19", "status": "affected" }, { "version": "0", "lessThan": "4.19", "status": "unaffected", "versionType": "semver" }, { "version": "4.19.318", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.280", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.222", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.163", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.100", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.41", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.10", "lessThanOrEqual": "6.9.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ 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"versionStartIncluding": "4.19", "versionEndExcluding": "6.9.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/7bb7670f92bfbd05fc41a8f9a8f358b7ffed65f4" }, { "url": "https://git.kernel.org/stable/c/d2346fca5bed130dc712f276ac63450201d52969" }, { "url": "https://git.kernel.org/stable/c/5d7e64d70a11d988553a08239c810a658e841982" }, { "url": "https://git.kernel.org/stable/c/04317a2471c2f637b4c49cbd0e9c0d04a519f570" }, { "url": "https://git.kernel.org/stable/c/e113cddefa27bbf5a79f72387b8fbd432a61a466" }, { "url": "https://git.kernel.org/stable/c/dfcdd7f89e401d2c6616be90c76c2fac3fa98fde" }, { "url": "https://git.kernel.org/stable/c/66cb64a1d2239cd0309f9b5038b05462570a5be1" }, { "url": "https://git.kernel.org/stable/c/97a9063518f198ec0adb2ecb89789de342bb8283" } ], "title": "tcp: avoid too many retransmit packets", 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