CVE-2026-43289

Description

In the Linux kernel, the following vulnerability has been resolved: kexec: derive purgatory entry from symbol kexec_load_purgatory() derives image->start by locating e_entry inside an SHF_EXECINSTR section. If the purgatory object contains multiple executable sections with overlapping sh_addr, the entrypoint check can match more than once and trigger a WARN. Derive the entry section from the purgatory_start symbol when present and compute image->start from its final placement. Keep the existing e_entry fallback for purgatories that do not expose the symbol. WARNING: kernel/kexec_file.c:1009 at kexec_load_purgatory+0x395/0x3c0, CPU#10: kexec/1784 Call Trace: <TASK> bzImage64_load+0x133/0xa00 __do_sys_kexec_file_load+0x2b3/0x5c0 do_syscall_64+0x81/0x610 entry_SYSCALL_64_after_hwframe+0x76/0x7e [[email protected]: move helper to avoid forward declaration, per Baoquan]

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (Versions prior to commits: 0277975, 1737d37, 36eb314, 480e1d5, 5226570)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * Conceptual PoC for CVE-2026-43289
 * Triggering the vulnerability requires crafting a purgatory ELF object
 * with multiple executable sections that have overlapping sh_addr.
 *
 * This C code demonstrates the structural requirement.
 */

#include <stdio.h>
#include <stdint.h>

// Simulated ELF Section Header structure for demonstration
typedef struct {
    uint32_t sh_name;
    uint32_t sh_type;
    uint64_t sh_flags;
    uint64_t sh_addr; // Virtual address
    uint64_t sh_offset;
    uint64_t sh_size;
    uint32_t sh_link;
    uint32_t sh_info;
    uint64_t sh_addralign;
    uint64_t sh_entsize;
} Elf64_Shdr;

int main() {
    printf("CVE-2026-43289 Conceptual Trigger\n");
    printf("Condition: Purgatory object with overlapping executable sections.\n");

    // To reproduce: Compile a purgatory object where two sections
    // (e.g., .text and .alt) are assigned the same or overlapping sh_addr.
    // Example Linker Script logic that causes the issue:
    //
    // SECTIONS
    // {
    //   . = 0x1000;
    //   .text : { *(.text) } /* sh_addr = 0x1000 */
    //   .text.alt : { *(.text.alt) } /* sh_addr = 0x1000 (Overlap!) */
    // }
    //
    // Loading this crafted object via kexec_load triggers the WARN.

    Elf64_Shdr sec1, sec2;
    sec1.sh_flags = 0x4 | 0x2; // SHF_ALLOC | SHF_EXECINSTR
    sec1.sh_addr = 0x1000;

    sec2.sh_flags = 0x4 | 0x2; // SHF_ALLOC | SHF_EXECINSTR
    sec2.sh_addr = 0x1000; // Overlapping address

    if (sec1.sh_addr == sec2.sh_addr && (sec1.sh_flags & 0x2)) {
        printf("[+] Malformed structure generated: Overlapping executable sections detected.\n");
        printf("[*] Result: Kernel WARN at kexec_load_purgatory+0x395/0x3c0\n");
    }

    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43289
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43289
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43289/
[4] VulDB https://vuldb.com/cve/CVE-2026-43289
[5] https://git.kernel.org/stable/c/027797595a108726f4a0a45d225f603b0ffbd22b
[6] https://git.kernel.org/stable/c/1737d37ae1d2814e6cf0a1af87af3d41f0812b95
[7] https://git.kernel.org/stable/c/36eb314184a0ae74dd42914b47d2b9fc43be8034
[8] https://git.kernel.org/stable/c/480e1d5c64bb14441f79f2eb9421d5e26f91ea3d
[9] https://git.kernel.org/stable/c/5226570bd252cea2e805a161cb0f75c204c3108a
[10] https://git.kernel.org/stable/c/875355152b33436907c2a6d2ffad1431fa86c62b
[11] https://git.kernel.org/stable/c/cfccd3b8c51bc57a8a6fcb2fd30453afae5bc0d2
[12] https://git.kernel.org/stable/c/f736032c638a33a243e9126e617788f763d648f9

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43289", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T14:16:35.867", "lastModified": "2026-05-15T16:24:16.027", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkexec: derive purgatory entry from symbol\n\nkexec_load_purgatory() derives image->start by locating e_entry inside an\nSHF_EXECINSTR section. If the purgatory object contains multiple\nexecutable sections with overlapping sh_addr, the entrypoint check can\nmatch more than once and trigger a WARN.\n\nDerive the entry section from the purgatory_start symbol when present and\ncompute image->start from its final placement. Keep the existing e_entry\nfallback for purgatories that do not expose the symbol.\n\nWARNING: kernel/kexec_file.c:1009 at kexec_load_purgatory+0x395/0x3c0, CPU#10: kexec/1784\nCall Trace:\n <TASK>\n bzImage64_load+0x133/0xa00\n __do_sys_kexec_file_load+0x2b3/0x5c0\n do_syscall_64+0x81/0x610\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\n[[email protected]: move helper to avoid forward declaration, per Baoquan]"}], "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": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.287", "versionEndExcluding": "4.20", "matchCriteriaId": "5245350E-E545-446D-A6C0-2E989F3977CB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.248", "versionEndExcluding": "5.5", "matchCriteriaId": "DB73E6A2-799F-4F3F-A41F-D941488D5BBE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.185", "versionEndExcluding": "5.10.252", "matchCriteriaId": "8E1F0730-BAF8-4DD0-8073-01A6332378F0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.118", "versionEndExcluding": "5.15.202", "matchCriteriaId": "33D0D77E-AD7A-466B-AD8C-882989B55DA0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.35", "versionEndExcluding": "6.1.165", "matchCriteriaId": "8E377CC8-FB48-457F-B230-4ED66CC1635A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3.9", "versionEndExcluding": "6.4", "matchCriteriaId": "0F0AC27C-C1AB-49CF-A549-0BF7D8370313"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4.1", "versionEndExcluding": "6.6.128", "matchCriteriaId": "ED949C60-54E9-4E38-BCA0-CA3FD1F24C5B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.75", "matchCriteriaId": "BCE16369-98ED-41CF-8995-DFDC10B288D2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.16", "matchCriteriaId": "B4B8CDA9-BADF-4CF5-8B3B-702DE8EEA40B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.6", "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.4:-:*:*:*:*:*:*", "matchCriteriaId": "DE0B0BF6-0EEF-4FAD-927D-7A0DD77BEE75"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.4:rc7:*:*:*:*:*:*", "matchCriteriaId": "1D6CAA59-F0EF-4E0B-8C23-EC9535008572"}, {"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: ... 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