CVE-2026-18772: Samsung rlottie Input Validation Flaw

CVE-2026-18772 Overview

CVE-2026-18772 is an improper input validation vulnerability [CWE-20] in Samsung Open Source rlottie, an animation library used to render Lottie files. The flaw allows oversized serialized data payloads to be processed without adequate bounds checks, leading to availability impact on the host application. Exploitation requires local access and user interaction, such as opening a crafted animation file in an application that links against rlottie. The issue is tracked in the Samsung rlottie GitHub Pull Request #596.

Critical Impact
Processing a malformed Lottie animation containing oversized serialized data can exhaust resources or crash the host application, producing a denial-of-service condition.

Affected Products

Samsung Open Source rlottie animation library
Applications and platforms that embed vulnerable versions of rlottie for Lottie animation rendering
Downstream software distributions bundling the affected library

Discovery Timeline

2026-08-04 - CVE-2026-18772 published to NVD
2026-08-04 - Last updated in NVD database

Technical Details for CVE-2026-18772

Vulnerability Analysis

The vulnerability resides in the deserialization path of rlottie, which parses JSON-based Lottie animation descriptors. The library fails to validate the size of serialized data structures before allocating or copying them into memory. When a crafted animation contains oversized arrays, keyframe lists, or shape descriptors, the parser proceeds without enforcing sane upper bounds.

The result is an availability impact on the calling process. Depending on the payload, the process may abort due to allocation failure, crash on an unchecked memory operation, or become unresponsive while parsing the malformed structure. Confidentiality and integrity are not affected, and the flaw does not enable code execution or privilege changes.

Remediation is tracked in Samsung rlottie Pull Request #596, which introduces input validation to reject oversized serialized payloads before allocation.

Root Cause

The root cause is missing input validation on serialized data length during Lottie deserialization. The parser trusts size fields present in untrusted input and does not enforce ceiling limits appropriate for legitimate animations. This is a classic [CWE-20] Improper Input Validation pattern applied to a media parser.

Attack Vector

An attacker delivers a crafted Lottie animation file to a victim through a channel supported by the target application, such as email attachment, chat message, downloaded asset, or bundled resource. The victim must open or render the file in an application backed by a vulnerable rlottie build. The vulnerability is exploitable locally with user interaction and cannot be triggered directly across a network boundary without a delivery mechanism.

No verified public exploit code exists for CVE-2026-18772. See Samsung rlottie Pull Request #596 for the technical fix and regression coverage.

Detection Methods for CVE-2026-18772

Indicators of Compromise

Repeated crashes or abnormal terminations in processes that load rlottie when opening animation assets
Presence of Lottie JSON files with unusually large arrays, keyframe counts, or shape lists relative to typical assets
Application logs showing allocation failures or parser aborts tied to Lottie rendering

Detection Strategies

Inventory software that links against rlottie and correlate versions against the fix introduced in Samsung rlottie Pull Request #596
Inspect ingested Lottie JSON files with schema validators that enforce reasonable maximums on array lengths and nesting depth
Alert on repeated crash telemetry from the same process when handling media assets from untrusted sources

Monitoring Recommendations

Collect and centralize crash dumps and process exit codes from client applications rendering Lottie content
Track file provenance for animation assets loaded by production applications, flagging externally sourced files
Monitor build pipelines and package manifests for rlottie versions predating the upstream fix

How to Mitigate CVE-2026-18772

Immediate Actions Required

Identify all deployed applications that embed rlottie and determine the linked version
Update rlottie to a build that incorporates the fix from Samsung rlottie Pull Request #596
Restrict rendering of Lottie animations sourced from untrusted origins until patched builds are deployed

Patch Information

The upstream fix is available in the Samsung rlottie repository via Pull Request #596. Downstream consumers should rebuild against a version that includes this change and redistribute updated binaries to end users. Applications that statically link rlottie require an application-level update rather than a system library update.

Workarounds

Pre-validate Lottie JSON assets with a schema that enforces maximum array sizes, object counts, and nesting depth before passing them to rlottie
Sandbox the process that renders untrusted animations so that crashes do not affect the parent application
Disable Lottie animation features in exposed workflows until updated rlottie binaries are deployed

bash

# Example: reject oversized Lottie JSON payloads before rendering
MAX_BYTES=$((512 * 1024))
for file in ./assets/*.json; do
  size=$(stat -c%s "$file")
  if [ "$size" -gt "$MAX_BYTES" ]; then
    echo "Rejecting oversized Lottie asset: $file ($size bytes)"
    mv "$file" ./quarantine/
  fi
done