CVE-2025-8835

Executive Summary

CVE-2025-8835 is a locally exploitable null pointer dereference vulnerability in the JasPer image processing library, affecting versions up to and including 4.2.5. The flaw resides in the jas_image_chclrspc function within src/libjasper/base/jas_image.c, specifically in the image color space conversion handler. An attacker with local access can trigger a null pointer dereference by providing a specially crafted image file, leading to a denial of service (application crash). The vulnerability has a CVSS score of 3.3 (Low), with a public proof-of-concept available. A patch has been released and is recommended for immediate application.

Supply Chain & Package Security

This vulnerability affects the JasPer library, which is a dependency for many image processing applications and systems. While not a direct package manager issue (NPM, PyPI, Go, Ruby), the library is commonly included in Linux distributions and embedded systems. Organizations should verify their software bill of materials (SBOM) for JasPer versions <= 4.2.5 and update to the patched version.

CVSS Breakdown & Threat Level

• CVSS Score: 3.3 (Low)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
• Attack Vector (AV): Local (L) – Requires local access to the system.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must open a malicious file.
• Scope (S): Unchanged (U) – Exploit cannot affect other components.
• Confidentiality (C): None (N) – No data exposure.
• Integrity (I): None (N) – No data modification.
• Availability (A): Low (L) – Application crash, but no persistent damage.

Threat Level: Low. The vulnerability requires local access and user interaction, and only results in a denial of service. However, in environments where image processing is critical, this could be leveraged for disruption.

Deep Dive & Mechanics

The vulnerability is a classic null pointer dereference in the jas_image_chclrspc function. This function is responsible for converting the color space of a JasPer image object. When processing a crafted image, the function attempts to access a pointer that has not been properly initialized or has been set to NULL. The specific code path involves the manipulation of color space conversion parameters, leading to a dereference of a NULL pointer.

The root cause is insufficient validation of the image's color space data before use. An attacker can craft an image file that, when parsed by JasPer, causes the jas_image_chclrspc function to operate on a NULL pointer, resulting in a segmentation fault and application crash.

Vulnerable vs. Patched Code

Vulnerable Code (<= 4.2.5): The vulnerable code in src/libjasper/base/jas_image.c does not check if a pointer returned from a color space lookup function is NULL before dereferencing it.

// Vulnerable snippet (conceptual)
jas_cmprof_t *prof = jas_cmprof_createfromclrspc(image->clrspc);
// No NULL check
jas_cmprof_t *newprof = jas_cmprof_copy(prof);

Patched Code (after commit bb7d62bd0a2a8e0e1fdb4d603f3305f955158c52): The patch adds a NULL check before using the pointer.

// Patched snippet (conceptual)
jas_cmprof_t *prof = jas_cmprof_createfromclrspc(image->clrspc);
if (!prof) {
    // Handle error, return or cleanup
    return -1;
}
jas_cmprof_t *newprof = jas_cmprof_copy(prof);

The exact patch can be viewed at the JasPer repository commit bb7d62bd0a2a8e0e1fdb4d603f3305f955158c52.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Local access to a system running JasPer <= 4.2.5.
• Ability to deliver a crafted image file to a user or process.

Exploitation Steps:

1. Craft a malicious image file that triggers the null pointer dereference. The exact structure depends on the JasPer image format (e.g., JPEG-2000, JPX). The PoC is publicly available.
2. Deliver the file to the target system via email, web download, or other means.
3. Wait for the victim to open the file with an application using the vulnerable JasPer library (e.g., image viewer, converter).
4. Observe the crash – the application will terminate unexpectedly.

Example PoC (conceptual):

# This is a conceptual representation. Actual PoC is public.
import struct

def create_malicious_jp2():
    # Craft a JP2 file with malformed color space data
    # ...
    with open('exploit.jp2', 'wb') as f:
        f.write(malicious_data)

create_malicious_jp2()

Blue Team

Detection:

• Monitor for crashes of applications that use JasPer (e.g., imagemagick, gimp, jasper itself).
• Look for segmentation faults in system logs (/var/log/syslog, dmesg).
• Use file integrity monitoring to detect the introduction of suspicious image files.

Mitigation:

• Apply the patch immediately.
• Restrict local access to systems running vulnerable JasPer versions.
• Use application whitelisting to prevent execution of untrusted image processing tools.
• Implement sandboxing for image processing tasks.

Indicators of Compromise (IOCs)

• File Hashes: (Specific to PoC – check public sources for exact hashes)
• File Names: exploit.jp2, malicious.jp2, crafted.jpx
• System Logs: Segmentation fault in jas_image_chclrspc or jasper process.
• Network: No network indicators (local exploit).
• Process: Crash of jasper, convert, display, or other image processing binaries.

Detection Engineering

YARA Rule

rule CVE_2025_8835_JasPer_Null_Pointer_Dereference {
    meta:
        description = "Detects crafted JP2 files targeting CVE-2025-8835"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-8835"
    strings:
        $magic = { 00 00 00 0C 6A 50 20 20 0D 0A 87 0A } // JP2 signature
        $color_space_marker = { 63 6C 72 73 } // "clrs" box
        $null_trigger = { 00 00 00 00 } // Potential null pointer trigger
    condition:
        $magic at 0 and $color_space_marker and #null_trigger > 2
}

Sigma Rule

title: CVE-2025-8835 JasPer Null Pointer Dereference
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects crashes of JasPer-based applications due to null pointer dereference
author: Valters IT
date: 2025-01-01
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith:
            - '/jasper'
            - '/convert'
            - '/display'
        CommandLine|contains: 'Segmentation fault'
    condition: selection
falsepositives:
    - Legitimate crashes due to other bugs
level: low

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-8835 JasPer Null Pointer Dereference - Potential Malicious JP2 Transfer"; flow:to_server; content:"|00 00 00 0C 6A 50 20 20 0D 0A 87 0A|"; depth:12; content:"|63 6C 72 73|"; distance:0; within:256; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

1. Apply the Patch: Update JasPer to a version that includes commit bb7d62bd0a2a8e0e1fdb4d603f3305f955158c52 or later.
2. Update Dependencies: Rebuild any applications that statically link JasPer.
3. Restrict Local Access: Limit user access to systems where image processing is critical.
4. User Education: Warn users not to open image files from untrusted sources.
5. Monitor Logs: Watch for application crashes and investigate suspicious image files.

Valters IT
Securing Digital Frontiers