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CVE Record

CVE-2021-36692: libjxl v0.3.7 is affected by a Divide By Zero in issue in lib/extras/codec_apng.cc jxl::DecodeImageAPNG().

libjxl v0.3.7 is affected by a Divide By Zero in issue in lib/extras/codec_apng.cc jxl::DecodeImageAPNG(). When encoding a malicous APNG file using cjxl, an attacker can trigger a denial of service.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-36692 is a denial-of-service issue in libjxl v0.3.7. A malicious APNG file processed through the cjxl encoder can trigger a divide-by-zero condition and crash processing. Business risk is mainly availability disruption where untrusted images are converted using affected libjxl tooling.

Executive priority

Prioritize remediation where image conversion supports customer uploads or other untrusted APNG content. For internal-only or unused cjxl deployments, urgency is lower. Treat this as an availability hardening issue unless additional vendor or threat intelligence changes the evidence.

Technical view

The reported flaw is in lib/extras/codec_apng.cc within jxl::DecodeImageAPNG(). The source bundle identifies libjxl v0.3.7 and cjxl APNG encoding as the affected path. Public references include a GitHub issue, pull request, and commit, but no CVSS score, CWE, CPE, or affected downstream products are provided.

Likely exposure

Exposure is most likely in systems that run libjxl v0.3.7 or cjxl against untrusted APNG files, such as media conversion, upload processing, or image pipeline services. The supplied CVE data does not identify downstream packaged products or CPEs.

Exploitation context

The source bundle describes a malicious APNG causing denial of service during encoding. CISA KEV status is false, and the provided sources do not claim active exploitation in the wild. No broader compromise, data exposure, or code execution is evidenced here.

Researcher notes

Evidence is narrow but credible: the CVE description, GitHub issue, pull request, and commit all point to an APNG decode divide-by-zero in libjxl v0.3.7. Missing CVSS, CWE, and CPE data limit precision for asset matching and severity scoring.

Mitigation direction

  • Check vendor guidance and libjxl release notes for the fixed version.
  • Update or rebuild libjxl with the referenced PR or commit included.
  • Avoid processing untrusted APNG files with affected cjxl builds.
  • Run image conversion in isolated workers with resource and restart controls.
  • Add monitoring for converter crashes or abnormal job failures.

Validation and detection

  • Inventory systems, containers, and build dependencies for libjxl and cjxl.
  • Confirm whether any deployed version is libjxl v0.3.7.
  • Verify whether APNG input reaches cjxl from users or external systems.
  • Check source or package provenance for the referenced fix commit.
  • Review logs for recurring APNG conversion crashes or job aborts.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.