{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64037", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.028Z", "datePublished": "2026-07-19T15:39:25.435Z", "dateUpdated": "2026-08-05T12:38:31.759Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:38:31.759Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled\n\nWhen the TLC notification disables AMSDU for a TID, the MLD driver sets\nmax_tid_amsdu_len to the sentinel value 1. The TSO segmentation path in\niwl_mld_tx_tso_segment() checks for zero but not for this sentinel,\nallowing it to reach the num_subframes calculation:\n\n num_subframes = (max_tid_amsdu_len + pad) / (subf_len + pad)\n = (1 + 2) / (1534 + 2) = 0\n\nThis zero propagates to iwl_tx_tso_segment() which sets:\n\n gso_size = num_subframes * mss = 0\n\nCalling skb_gso_segment() with gso_size=0 creates over 32000 tiny\nsegments from a single GSO skb. This floods the TX ring with ~1024\nmicro-frames (the rest are purged), creating a massive burst of TX\ncompletion events that can lead to memory corruption and a subsequent\nuse-after-free in TCP's retransmit queue (refcount underflow in\ntcp_shifted_skb, NULL deref in tcp_rack_detect_loss).\n\nThe MVM driver is immune because it checks mvmsta->amsdu_enabled before\nreaching the num_subframes calculation. The MLD driver has no equivalent\nbitmap check and relies solely on max_tid_amsdu_len, which does not\ncatch the sentinel value.\n\nFix this by detecting the sentinel value (max_tid_amsdu_len == 1) at the\nexisting check and falling back to non-AMSDU TSO segmentation. Also add\na WARN_ON_ONCE guard after the num_subframes division as defense-in-depth\nto catch any future code paths that produce zero through a different\nmechanism." } ], "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 - A remote peer can trigger the vulnerable iwlwifi MLD TX/TSO path by inducing large outbound TCP traffic (responses, uploads, or sustained transfers) on a WiFi 7 Intel system; no adjacent WiFi frame injection or local syscall access is required to reach the bug.\nAC:L - An attacker controls the timing and volume of TCP traffic that produces GSO skbs, and TLC AMSDU-disable notifications are normal firmware rate-adaptation behavior that occurs during routine WiFi use; repeated attempts can reliably hit the sentinel state without conditions outside attacker influence.\nPR:N - Exploitation requires only the ability to generate or solicit network traffic on the victim's WiFi interface; no local account, CAP_NET_ADMIN, or root privileges are needed on the victim host.\nUI:N - No victim user action beyond normal automated network activity is required; a remote attacker can trigger the condition with crafted or high-volume TCP sessions alone.\nS:U - The resulting memory corruption and TCP retransmit-queue UAF occur within kernel/network-driver scope and do not cross a VM, container, or IOMMU security boundary.\nC:H - The fix commit documents memory corruption and a subsequent use-after-free in TCP's retransmit queue (refcount underflow in tcp_shifted_skb), which per kernel guidance enables arbitrary kernel memory read primitives.\nI:H - The same UAF and refcount corruption in the TCP retransmit path can be leveraged for arbitrary kernel writes and potential control-flow hijacking, not merely a bounded data change.\nA:H - The segmentation explosion floods the TX ring with ~1024 micro-frames and a burst of completion events, causing kernel instability including NULL dereference in tcp_rack_detect_loss and system crash/hang." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/wireless/intel/iwlwifi/mld/tx.c" ], "versions": [ { "version": "d1e879ec600f9b3bdd253167533959facfefb17b", "lessThan": "9e360e610a73f62432e986775023d5382773f045", "status": "affected", "versionType": "git" }, { "version": "d1e879ec600f9b3bdd253167533959facfefb17b", "lessThan": "cbe1c8245e4469d1aa6e12e5d913611376d23788", "status": "affected", "versionType": "git" }, { "version": "d1e879ec600f9b3bdd253167533959facfefb17b", "lessThan": "92cee08dc4f00e77fd1317e4343c5d458b0abab7", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/wireless/intel/iwlwifi/mld/tx.c" ], "versions": [ { "version": "6.15", "status": "affected" }, { "version": "0", "lessThan": "6.15", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.34", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.11", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "6.18.34" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.0.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/9e360e610a73f62432e986775023d5382773f045" }, { "url": "https://git.kernel.org/stable/c/cbe1c8245e4469d1aa6e12e5d913611376d23788" }, { "url": "https://git.kernel.org/stable/c/92cee08dc4f00e77fd1317e4343c5d458b0abab7" } ], "title": "wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled", "x_generator": { "engine": "bippy-1.2.0" } } } }