{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64089", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.032Z", "datePublished": "2026-07-19T15:39:58.729Z", "dateUpdated": "2026-08-05T12:39:06.132Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:39:06.132Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: tt: fix negative last_changeset_len\n\nbatadv_piv_tt::last_changeset_len len was declared as s16, but the field is\nnever intended to hold a negative value. When a value greater than 32767 is\nassigned, it wraps to a negative signed integer.\n\nIn batadv_send_my_tt_response(), last_changeset_len is temporarily widened\nto s32. The incorrectly negative s16 value propagates into the s32, causing\nbatadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but\npopulates only a small portion of it with the collected changeset. All\nremaining bits are kept uninitialized.\n\nUsing an u16 avoids this type confusion and ensures that no (negative) sign\nextension is performed in batadv_send_my_tt_response()." } ], "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 reached when a remote mesh peer's TT_REQUEST is processed via batman-adv's network receive path (batadv_recv_unicast_tvlv), which handles ETH_P_BATMAN packets from network-facing mesh interfaces without requiring local access.\nAC:L - Once the victim has a wrapped last_changeset_len (achievable on high-MTU mesh nodes with >2730 TT changes), the attacker reliably triggers the bug by sending a crafted TT_REQUEST with matching ttvn and without BATADV_TT_FULL_TABLE; no race or victim-dependent timing is required.\nPR:N - Exploitation requires only the ability to send batman-adv protocol packets as a mesh peer; no account, credentials, or elevated privileges on the victim system are needed, and TT_REQUEST handling has no authentication gate beyond being a known originator in the mesh.\nUI:N - The victim administrator or end user need take no action during exploitation; the attacker sends a TT_REQUEST and the kernel processes it automatically in response to received mesh traffic.\nS:U - The vulnerability corrupts kernel heap memory and leaks kernel data within the kernel's own security boundary; it does not cross into another security authority such as a VM guest-to-host or sandbox escape.\nC:H - Sign-extended negative last_changeset_len causes memcpy() to read far beyond the small last_changeset buffer (OOB heap read), and the oversized kmalloc response buffer retains uninitialized kernel memory that is copied into the TT_RESPONSE sent back to the attacker.\nI:H - The same memcpy() with a sign-extended negative length writes far beyond the allocated tt_change region in the kmalloc buffer, causing out-of-bounds heap corruption that can be leveraged for arbitrary kernel writes or control-flow hijacking.\nA:H - The massive out-of-bounds memcpy() from a wrapped s16 length will cause kernel memory corruption, oops, or panic, and even partial execution leaks uninitialized data before potential crash." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/batman-adv/types.h" ], "versions": [ { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "6314089acf0ddf64376fdc0b1420695504c73f52", "status": "affected", "versionType": "git" }, { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "55dc41fe8821e9a849e147255ad572bc933a9d15", "status": "affected", "versionType": "git" }, { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "c424e8519ac78eac5d9f4eecf06208a0d619ec14", "status": "affected", "versionType": "git" }, { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "22d59c72f4a47ffec121d0610f70d0d70c3c11c8", "status": "affected", "versionType": "git" }, { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "eb235472b52ef36981c5aad330485eaf2382c53b", "status": "affected", "versionType": "git" }, { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "179eb62506a02d00370bd6478898cb632e10986c", "status": "affected", "versionType": "git" }, { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "d29abf70c665730e249d2ec8e1402095ae26bcee", "status": "affected", "versionType": "git" }, { "version": "a73105b8d4c765d9ebfb664d0a66802127d8e4c7", "lessThan": "fc92cdfcb295cefa4344d71a527d61b638b7bfc4", "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/batman-adv/types.h" ], "versions": [ { "version": "3.1", "status": "affected" }, { "version": "0", "lessThan": "3.1", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.258", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.209", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.175", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.142", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.92", "lessThanOrEqual": "6.12.*", "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": "3.1", "versionEndExcluding": "5.10.258" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "5.15.209" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.1.175" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.6.142" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.12.92" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "6.18.34" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "7.0.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/6314089acf0ddf64376fdc0b1420695504c73f52" }, { "url": "https://git.kernel.org/stable/c/55dc41fe8821e9a849e147255ad572bc933a9d15" }, { "url": "https://git.kernel.org/stable/c/c424e8519ac78eac5d9f4eecf06208a0d619ec14" }, { "url": "https://git.kernel.org/stable/c/22d59c72f4a47ffec121d0610f70d0d70c3c11c8" }, { "url": "https://git.kernel.org/stable/c/eb235472b52ef36981c5aad330485eaf2382c53b" }, { "url": "https://git.kernel.org/stable/c/179eb62506a02d00370bd6478898cb632e10986c" }, { "url": "https://git.kernel.org/stable/c/d29abf70c665730e249d2ec8e1402095ae26bcee" }, { "url": "https://git.kernel.org/stable/c/fc92cdfcb295cefa4344d71a527d61b638b7bfc4" } ], "title": "batman-adv: tt: fix negative last_changeset_len", "x_generator": { "engine": "bippy-1.2.0" } } } }