CVE-2026-84383

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 51% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

libheif is a HEIF and AVIF file format decoder and encoder. From 1.22.0 until 1.23.2, a crafted HEIF, HEIC, or AVIF item graph using nested iden and auxl references can make HeifPixelImage::transfer_channel_from_image_as() append duplicate Alpha planes with different bit depths to m_storage. HeifPixelImage::scale_nearest_neighbor() in libheif/image/pixelimage.cc allocates the destination Alpha plane using the first plane's 8-bit depth, then iterates a later 10-bit or 12-bit Alpha component and writes uint16_t samples into the same 8-bit allocation. The output geometry controls the overflow extent and the encoded sample values control the data written, allowing a remote file processed by heif_decode_image() to cause a heap out-of-bounds write. This issue is fixed in version 1.23.2.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
49%
KEV
Not listed

Published

September 18, 2026

Last Modified

September 18, 2026

Advisory Details (3)

Auto-updated Sep 18, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available

Heap buffer overflow in `scale_nearest_neighbor()` via duplicate Alpha planes from nested `iden`/`auxl` items · Advisory · strukturag/libheif · GitHub

https://github.com/strukturag/libheif/security/advisories/GHSA-g89c-p67h-r497
github_release Patch Available

v1.23.2 - security release

Patch available: strukturag/libheif v1.23.2

https://github.com/strukturag/libheif/releases/tag/v1.23.2
github_commit Patch Available

commit f4fb8bde4704 (strukturag/libheif)

Patch available: strukturag/libheif v1.23.2 (contains commit f4fb8bde4704)

https://github.com/strukturag/libheif/commit/f4fb8bde4704ebb46e46ff9fb94407c9774153b2

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 4× in last 7d / 4× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 16:29 UTCEG score recompute
  2. 2026-09-18 16:25 UTCEG score recompute
  3. 2026-09-18 16:02 UTCEG score recompute
  4. 2026-09-18 15:59 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-84383?
CVE-2026-84383 is a critical vulnerability published on September 18, 2026. libheif is a HEIF and AVIF file format decoder and encoder. From 1.22.0 until 1.23.2, a crafted HEIF, HEIC, or AVIF item graph using nested iden and auxl references can make HeifPixelImage::transferchannelfromimageas() append duplicate Alpha planes with different bit depths to mstorage.…
When was CVE-2026-84383 disclosed?
CVE-2026-84383 was first published in the National Vulnerability Database on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84383 actively exploited?
CVE-2026-84383 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 50.7% of all scored CVEs.
What is the CVSS score of CVE-2026-84383?
CVE-2026-84383 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-84383?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84383, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-84383

Explore →

Is Your Infrastructure Affected by CVE-2026-84383?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs