CVE-2026-52492 Overview
CVE-2026-52492 is an integer overflow vulnerability in the rgb2ycbcr utility shipped with libtiff. The flaw resides in the cvtRaster() function, which miscalculates strip buffer sizes when processing a crafted TIFF image. The arithmetic overflow produces an undersized heap allocation, and the subsequent YCbCr conversion writes past the allocated buffer. This heap-based buffer overflow can corrupt adjacent memory during local processing of an attacker-supplied file. The vulnerability is tracked under CWE-190 (Integer Overflow or Wraparound).
Critical Impact
A crafted TIFF file processed by rgb2ycbcr can trigger heap corruption, enabling arbitrary code execution, data tampering, or denial of service in the context of the invoking user.
Affected Products
- libtiff rgb2ycbcr utility (upstream project)
- Applications and distributions bundling vulnerable libtiff builds
- Downstream image-processing pipelines invoking rgb2ycbcr
Discovery Timeline
- 2026-08-24 - CVE-2026-52492 published to NVD
- 2026-08-27 - Last updated in NVD database
Technical Details for CVE-2026-52492
Vulnerability Analysis
The rgb2ycbcr utility converts RGB TIFF images to YCbCr encoding. Inside cvtRaster(), libtiff computes the size of the per-strip working buffer based on image dimensions and sample counts derived from TIFF tags. When these values are large or maliciously crafted, the multiplication used to determine the allocation size wraps around the fixed-width integer range. The resulting truncated value is passed to the heap allocator, which returns a buffer far smaller than the conversion routine actually requires. The YCbCr transformation then iterates across the true, unwrapped extent and writes beyond the allocation. Attackers can shape adjacent heap metadata and object contents to achieve control-flow hijacking or memory disclosure.
Root Cause
The root cause is unchecked integer arithmetic when sizing the strip buffer. The cvtRaster() function does not validate that the product of width, height, and bytes-per-sample fits within the destination integer type before invoking allocation. The upstream fix in libtiff commit 94affc5c introduces overflow-safe size computation and rejects images whose parameters exceed representable bounds.
Attack Vector
Exploitation requires local access and user interaction. An attacker delivers a crafted TIFF file, and a victim runs rgb2ycbcr against it, either directly or through an automated conversion workflow. Successful exploitation grants attacker-controlled writes on the heap within the process performing the conversion. See the proof-of-concept gist for reproduction details.
Detection Methods for CVE-2026-52492
Indicators of Compromise
- Unexpected crashes or SIGABRT signals from rgb2ycbcr processes with heap corruption diagnostics such as malloc_consolidate or free(): invalid pointer.
- TIFF files with anomalously large ImageWidth, ImageLength, or SamplesPerPixel header values that overflow 32-bit size arithmetic.
- Child processes spawned by image-conversion services that terminate abnormally after ingesting user-submitted TIFF assets.
Detection Strategies
- Inventory hosts running libtiff builds predating the upstream fix commit 94affc5c and flag any that invoke rgb2ycbcr in automated pipelines.
- Instrument conversion utilities with AddressSanitizer or heap-hardening allocators in test environments to surface out-of-bounds writes.
- Correlate process crashes of rgb2ycbcr with the file paths of recently processed TIFFs to identify malicious inputs.
Monitoring Recommendations
- Log invocations of rgb2ycbcr and capture the source, size, and hash of input TIFF files.
- Alert on segmentation faults, glibc heap error messages, or coredumps originating from libtiff utilities.
- Monitor image ingestion services for spikes in malformed TIFF submissions or repeated conversion failures from the same source.
How to Mitigate CVE-2026-52492
Immediate Actions Required
- Upgrade libtiff to a build that includes the fix in commit 94affc5c or later.
- Remove or disable the rgb2ycbcr utility on hosts where it is not required.
- Restrict acceptance of TIFF files from untrusted sources in automated conversion workflows.
Patch Information
The upstream libtiff project resolved the integer overflow in GitLab commit 94affc5cf54111312f9891eb77accb93eebc28d7. The patch adds bounded size computation in cvtRaster() and aborts conversion when the derived buffer size would overflow. Rebuild dependent packages against the patched libtiff and redeploy any container images or appliances that embed the library.
Workarounds
- Validate TIFF metadata before conversion and reject files whose dimensions or sample counts exceed application limits.
- Execute rgb2ycbcr inside a sandbox, seccomp profile, or unprivileged container with no access to sensitive data.
- Replace rgb2ycbcr in pipelines with an alternative converter until patched packages are deployed.
# Verify installed libtiff version and rebuild against the fixed commit
tiffinfo -v 2>&1 | head -n 1
git clone https://gitlab.com/libtiff/libtiff.git
cd libtiff && git checkout 94affc5cf54111312f9891eb77accb93eebc28d7
./autogen.sh && ./configure && make && sudo make install
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