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CVE-2026-8814 ExifReader CVE debrief

CVE-2026-8814 documents a data amplification vulnerability in ExifReader, a JavaScript library for reading image metadata. Versions prior to 4.39.0 fail to enforce maximum decompressed output size limits when handling PNG zTXt (compressed text) metadata chunks. When asynchronous parsing is enabled, a crafted PNG file containing a highly compressed zTXt chunk can trigger disproportionate memory consumption as the library materializes an oversized Comment value. This represents an Improper Handling of Highly Compressed Data (Data Amplification) weakness (CWE-409). The vulnerability carries a MEDIUM severity CVSS 4.0 score of 5.5 with an Attack Vector of Network, Attack Complexity Low, and Availability impact Low. The issue was reported via Snyk and disclosed on 2026-05-19. A fix has been committed to the ExifReader repository.

Vendor
ExifReader
Product
ExifReader
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-19
Original CVE updated
2026-07-23
Advisory published
2026-05-19
Advisory updated
2026-07-23

Who should care

Organizations running server-side image processing services using ExifReader, particularly those accepting user-uploaded PNG files. Developers using ExifReader in asynchronous mode for metadata extraction pipelines. Security teams monitoring for resource exhaustion vulnerabilities in JavaScript dependency chains.

Technical summary

The ExifReader library's PNG zTXt chunk handler performs zlib decompression without enforcing a maximum output size bound. A malicious actor can craft a PNG with a small, highly compressed zTXt chunk that expands to a very large string when decompressed. When `async` parsing mode is used, this results in uncontrolled memory allocation for the Comment field. The vulnerability is classified as data amplification (CWE-409) rather than traditional memory corruption, as it exploits legitimate decompression functionality without proper resource limits. The CVSS 4.0 vector indicates network attackability with low complexity and low availability impact, consistent with a denial-of-service via resource exhaustion scenario.

Defensive priority

medium

Recommended defensive actions

  • Upgrade ExifReader to version 4.39.0 or later to obtain the size-limiting fix for PNG zTXt decompression
  • Review applications using ExifReader with asynchronous parsing enabled, as this configuration is required for the vulnerability to be exploitable
  • Implement input validation to reject or quarantine untrusted PNG files before metadata extraction
  • Consider memory limits and resource constraints in server-side image processing pipelines using ExifReader
  • Monitor for updates to NVD record status from Deferred to finalized analysis

Evidence notes

Vulnerability identified by Snyk security research. Fix commit available in official repository. NVD status currently Deferred.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-8814 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-8814

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-8814 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-8814

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.