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The vulnerability is a classic heap-based buffer overflow (CWE-122) that occurs in the `NewXMLTree()` method when ImageMagick parses a crafted XML file. In essence, the product fails to perform proper bounds checking before writing a null terminator byte (0x00) to a heap-allocated buffer.
During XML tree construction, the `NewXMLTree()` method calculates the required memory size for a buffer. Due to a boundary error, the algorithm miscalculates the buffer’s end, leading to an off-by-one error. When the method attempts to append a terminating zero byte, it writes one position past the allocated memory region, corrupting adjacent heap metadata or application data.
This out-of-bounds write is not a massive corruption—it is a single zero byte. However, even this minimal corruption can corrupt critical heap structures (e.g., free-list pointers or size fields), leading to an immediate application crash or, under certain memory layouts, paving the way for further exploitation.
The issue is triggered remotely without authentication, as an attacker can supply a specially crafted image or XML input to any application that uses the vulnerable ImageMagick version. No user interaction is required, making it a low-complexity, network-based attack vector.
The root cause stems from improper buffer boundary validation within the `NewXMLTree` method. When building the XML tree, the method fails to reserve enough space for the final null terminator, resulting in a write that lands in unallocated memory. This is a typical CWE-787 (Out-of-Bounds Write) weakness, where the software writes data past the end of the intended buffer.
Because ImageMagick is widely deployed in server-side image processing pipelines (web apps, CMSs, automated converters), this vulnerability can be used to cause denial-of-service (DoS) by crashing the process.
No public exploit is currently available, but the flaw is easily reproducible with a malformed input file. The vulnerability was discovered through fuzzing, and patches have been released to fix the boundary miscalculation.
dailycve form:
Platform: ImageMagick
Version: <7.1.2-17 / <6.9.13-42
Vulnerability: Out-of-bounds Write
Severity: Medium (5.3)
date: 2026-03-18
Prediction: 2026-04-15
What Undercode Say:
Bash commands to check your ImageMagick version and detect vulnerable installations:
Check ImageMagick version identify -version For Debian/Ubuntu systems dpkg -l | grep imagemagick For RHEL/CentOS/Fedora rpm -qa | grep ImageMagick Quick check using a test file (crash trigger) convert -size 1x1 xc:white test.png convert test.png -format "%[fx:1/0]" info: Not the exploit, but a safe crash test
Exploit:
No public exploit exists at this time. However, an attacker would craft a malformed XML file (e.g., a malicious MSL or SVG file) that triggers the off-by-one error in NewXMLTree(). When processed by a vulnerable ImageMagick version, the single zero byte is written beyond the heap buffer, corrupting adjacent memory and causing a segmentation fault (crash).
Protection from this CVE
- Upgrade to ImageMagick 7.1.2-17 (7.x branch) or 6.9.13-42 (6.x branch).
- If using Magick.NET, upgrade to version 14.11.0 or higher.
- As a workaround, disable XML-based formats (MSL, SVG, MVG) by modifying
policy.xml:<policy domain="coder" rights="none" pattern="MSL" /> <policy domain="coder" rights="none" pattern="SVG" />
- Restrict input to trusted sources only, and validate file types before processing.
Impact
- Availability: High impact – remote attacker can cause a denial-of-service (crash).
- Integrity: None – the write is limited to a single zero byte, no data modification.
- Confidentiality: None – no information disclosure.
- Overall Severity: Medium (CVSS 5.3).
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Sources:
Reported By: github.com
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