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GHSA-fhp4-pr5j-46m5

HighCVSS 7.5 / 10
Published Jun 26, 2026·Last modified Jun 26, 2026
Affected Components(0)

No affected components available

Description

Summary

A NULL pointer dereference vulnerability exists in PDFParser::CreateFilterForStream() when processing a PDF stream with /Filter /LZWDecode and a /DecodeParms dictionary that does not contain the EarlyChange key. This causes an access violation (0xC0000005) and crashes the process.

Affected Version

muhammara <= 6.0.4 (latest)

Vulnerability Details

File: src/deps/PDFWriter/PDFParser.cpp line 2107

if (inDecodeParams)
{
    PDFObjectCastPtr<PDFInteger> earlyObj(
        QueryDictionaryObject(inDecodeParams, "EarlyChange")
    );
    early = earlyObj->GetValue();  // NULL dereference when EarlyChange key is absent
}

When inDecodeParams is non-NULL but lacks the EarlyChange key:

  1. QueryDictionaryObject() returns NULL
  2. PDFObjectCastPtr<PDFInteger>(NULL) wraps NULL
  3. earlyObj->GetValue() dereferences NULL → crash

PoC

460-byte malicious PDF triggers crash via startReadingFromStream():

  • PDF contains /Filter /LZWDecode with /DecodeParms << >> (empty, no EarlyChange)
  • Exit code: 0xC0000005 (Access Violation)

Fix

if (earlyObj)
    early = earlyObj->GetValue();

Impact

Any application accepting untrusted PDFs and using muhammara to read stream contents is vulnerable to DoS.

Similar to: CVE-2022-41957, CVE-2022-39381

PoC File

poc_muhammara_lzw_null.js

Risk Scores
Base Score
7.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
6.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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