CVE-2026-22991

Description

In the Linux kernel, the following vulnerability has been resolved: libceph: make free_choose_arg_map() resilient to partial allocation free_choose_arg_map() may dereference a NULL pointer if its caller fails after a partial allocation. For example, in decode_choose_args(), if allocation of arg_map->args fails, execution jumps to the fail label and free_choose_arg_map() is called. Since arg_map->size is updated to a non-zero value before memory allocation, free_choose_arg_map() will iterate over arg_map->args and dereference a NULL pointer. To prevent this potential NULL pointer dereference and make free_choose_arg_map() more resilient, add checks for pointers before iterating.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux kernel libceph (未修补版本)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* PoC concept for CVE-2026-22991 NULL pointer dereference
 * This demonstrates the vulnerability in libceph's free_choose_arg_map()
 * 
 * The vulnerability occurs when:
 * 1. arg_map->size is set to non-zero value
 * 2. arg_map->args allocation fails (returns NULL)
 * 3. free_choose_arg_map() is called with non-zero size but NULL args
 * 4. The function iterates over args and dereferences NULL pointer
 */

struct choose_arg_map {
    size_t size;
    void **args;  // NULL when allocation fails
};

void free_choose_arg_map_vulnerable(struct choose_arg_map *arg_map) {
    // Vulnerable: iterates without checking if args is NULL
    for (size_t i = 0; i < arg_map->size; i++) {
        free(arg_map->args[i]);  // NULL pointer dereference here
    }
    free(arg_map->args);
    free(arg_map);
}

void free_choose_arg_map_fixed(struct choose_arg_map *arg_map) {
    // Fixed: check args before iterating
    if (arg_map->args != NULL) {
        for (size_t i = 0; i < arg_map->size; i++) {
            free(arg_map->args[i]);
        }
        free(arg_map->args);
    }
    free(arg_map);
}

int trigger_vulnerability(void) {
    struct choose_arg_map *arg_map = malloc(sizeof(struct choose_arg_map));
    if (!arg_map) return -1;
    
    // Simulate partial allocation failure scenario
    arg_map->size = 10;  // Set size before allocation
    arg_map->args = NULL;  // Allocation would fail here in real scenario
    
    // This will trigger NULL pointer dereference
    free_choose_arg_map_vulnerable(arg_map);
    
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-22991
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-22991
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-22991/
[4] VulDB https://vuldb.com/cve/CVE-2026-22991
[5] https://git.kernel.org/stable/c/8081faaf089db5280c3be820948469f7c58ef8dd
[6] https://git.kernel.org/stable/c/851241d3f78a5505224dc21c03d8692f530256b4
[7] https://git.kernel.org/stable/c/9b3730dabcf3764bfe3ff07caf55e641a0b45234
[8] https://git.kernel.org/stable/c/c4c2152a858c0ce4d2bff6ca8c1d5b0ef9f2cbdf
[9] https://git.kernel.org/stable/c/e3fe30e57649c551757a02e1cad073c47e1e075e
[10] https://git.kernel.org/stable/c/ec1850f663da64842614c86b20fe734be070c2ba
[11] https://git.kernel.org/stable/c/f21c3fdb96833aac2f533506899fe38c19cf49d5

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-22991", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-01-23T16:15:55.183", "lastModified": "2026-04-27T14:16:28.150", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: make free_choose_arg_map() resilient to partial allocation\n\nfree_choose_arg_map() may dereference a NULL pointer if its caller fails\nafter a partial allocation.\n\nFor example, in decode_choose_args(), if allocation of arg_map->args\nfails, execution jumps to the fail label and free_choose_arg_map() is\ncalled. Since arg_map->size is updated to a non-zero value before memory\nallocation, free_choose_arg_map() will iterate over arg_map->args and\ndereference a NULL pointer.\n\nTo prevent this potential NULL pointer dereference and make\nfree_choose_arg_map() more resilient, add checks for pointers before\niterating."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nlibceph: hacer free_choose_arg_map() resistente a la asignación parcial\n\nfree_choose_arg_map() puede desreferenciar un puntero NULL si su llamador falla después de una asignación parcial.\n\nPor ejemplo, en decode_choose_args(), si la asignación de arg_map->args falla, la ejecución salta a la etiqueta fail y se llama a free_choose_arg_map(). Dado que arg_map->size se actualiza a un valor distinto de cero antes de la asignación de memoria, free_choose_arg_map() iterará sobre arg_map->args y desreferenciará un puntero NULL.\n\nPara evitar esta potencial desreferencia de puntero NULL y hacer free_choose_arg_map() más resistente, añadir comprobaciones para los punteros antes de iterar."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"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", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}, {"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-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "5.10.248", "matchCriteriaId": "14DEF845-E647-4A78-9311-A8F1A59E3A66"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.198", "matchCriteriaId": "82159CAA-B6BA-43C6-85D8-65BDBC175A7E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.161", "matchCriteriaId": "E135B7E2-61FC-4DC1-8570-ABD67894FFDE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.121", "matchCriteriaId": "BB7A164B-7422-4A1C-82FB-5FCAEE53C06C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.66", "matchCriteriaId": "F72B884C-B44F-40E4-9895-CE421AC663D0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.6", "matchCriteriaId": "879529BC-5B4C-4EBE-BF1D-1A31404A8B2E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc1:*:*:*:*:*:*", "matchCriteriaId": "17B67AA7-40D6-4AFA-8459-F200F3D7CFD1"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc2:*:*:*:*:*:*", "matchCriteriaId": "C47E4CC9-C826-4FA9-B014-7FE3D9B318B2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc3:*:*:*:*:*:*", "matchCriteriaId": "F71D92C0-C023-48BD-B3B6-70B638EEE298"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc4:*:*:*:*:*:*", "matchCriteriaId": "13580667-0A98-40CC-B29F-D12790B91BDB"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/8081faaf089db5280c3be820948469f7c58ef8dd", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/851241d3f78a5505224 ... 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