CVE-2025-61143: Libtiff NULL Pointer Dereference Flaw

CVE-2025-61143 Overview

CVE-2025-61143 is a NULL pointer dereference vulnerability affecting libtiff versions up to and including v4.7.1. The flaw resides in the libtiff/tif_open.c component, which handles TIFF file opening operations. An attacker can trigger the dereference by supplying a crafted TIFF file to an application that links against the vulnerable library. Successful exploitation causes the consuming process to crash, resulting in denial of service. The issue is tracked under CWE-476: NULL Pointer Dereference.

Critical Impact
Local processing of a malicious TIFF file causes libtiff-linked applications to crash, denying service to image processing pipelines, document viewers, and converters that rely on the library.

Affected Products

libtiff versions up to and including v4.7.1
Applications and services that link against vulnerable libtiff builds
Image processing pipelines that parse TIFF files through libtiff

Discovery Timeline

2026-02-23 - CVE-2025-61143 published to NVD
2026-02-25 - Last updated in NVD database

Technical Details for CVE-2025-61143

Vulnerability Analysis

The vulnerability is a NULL pointer dereference in the TIFF file open routine implemented in libtiff/tif_open.c. When libtiff processes a malformed or specifically crafted TIFF file, internal state initialization fails to allocate or assign a required pointer. Subsequent code paths dereference that NULL pointer without validating it, causing an immediate segmentation fault. The defect is contained within the library, so any caller invoking TIFFOpen or related functions on attacker-controlled input is exposed.

Root Cause

The root cause is missing validation of a pointer before dereference inside tif_open.c. Parsing logic assumes that prior initialization steps always produce a valid object reference. When a crafted TIFF header bypasses or skips that initialization, the pointer remains NULL. The code then accesses fields through the NULL pointer, triggering the crash. This is a classic CWE-476 pattern in C-based image parsers.

Attack Vector

Exploitation requires local access and user interaction, typically opening or processing the malicious TIFF file. The vulnerability does not yield code execution, confidentiality loss, or integrity loss. Impact is restricted to availability through process termination. An attacker can weaponize the flaw against batch converters, thumbnailers, and document workflows that automatically parse TIFF inputs. Headless services that ingest TIFF uploads may experience repeated crashes if the malicious file is reprocessed.

The vulnerability manifests during TIFF descriptor initialization. See the GitLab issue and merge request for technical specifics and the upstream fix.

Detection Methods for CVE-2025-61143

Indicators of Compromise

Unexpected crashes or segmentation faults in processes that load libtiff, including viewers, converters, and thumbnail generators.
Core dumps with faulting addresses inside tif_open.c call paths.
Repeated parser failures tied to the same TIFF file across hosts or queues.

Detection Strategies

Inventory installed libtiff versions across endpoints and servers, flagging any build at or below v4.7.1.
Monitor application logs for abnormal termination events from image processing services.
Correlate user-submitted TIFF uploads with downstream parser crashes in ingestion pipelines.

Monitoring Recommendations

Enable crash reporting and core dump collection on hosts running TIFF-handling workloads.
Alert on repeated SIGSEGV exits from processes such as convert, tiffinfo, or custom services linking libtiff.
Track file hashes of TIFF inputs that precede service crashes to identify malicious samples.

How to Mitigate CVE-2025-61143

Immediate Actions Required

Identify all systems and container images bundling libtiff v4.7.1 or earlier.
Restrict acceptance of untrusted TIFF files in automated pipelines until patched.
Apply the upstream fix from the libtiff merge request once distributed in a tagged release.

Patch Information

The upstream libtiff project tracks the defect in issue 737 with the corrective change in merge request 755. Apply the fixed release from your operating system vendor or rebuild dependent applications against a patched libtiff once a release later than v4.7.1 incorporating the fix is available. A reproducer is documented in this GitHub gist.

Workarounds

Validate TIFF inputs with a stricter pre-parser or sandbox the parsing process to contain crashes.
Run image processing in isolated workers with automatic restart so a crash does not halt the broader service.
Reject TIFF files from untrusted sources at the application boundary until patched libraries are deployed.

bash

# Configuration example: identify vulnerable libtiff installs
dpkg -l | grep -i libtiff
rpm -qa | grep -i libtiff
ldconfig -p | grep libtiff