CVE-2026-84383

CRITICALPre-NVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 9.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7% (53rd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated

Also known asEUVD-2026-83019 (ENISA EUVD)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 9.8Exploit: Public PoCExposed services: Not assessed

A fix is available — apply it.

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
9.8CRITICALmedium confidence
EG Risk
75
EG Risk 75/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.7%
EPSS %ILE
53rd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

September 18, 2026

Last Modified

September 18, 2026

Advisory Details (3)

Auto-updated Oct 31, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
GitHub advisoryMentions a patch (unverified)🟡 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

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libheif1.19.8-1 ... 1.23.1-1 (9 versions)
  • every version up to 1.23.2-1: fixed in 1.23.2-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 62× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-11-02 15:08 UTCEG score recompute
  2. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  3. 2026-10-31 17:31 UTCEG score recompute
  4. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  5. 2026-10-30 18:43 UTCEG score recompute
  6. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  7. 2026-10-29 19:56 UTCEG score recompute
  8. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  9. 2026-10-28 21:10 UTCEG score recompute
  10. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  11. 2026-10-27 22:20 UTCEG score recompute
  12. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  13. 2026-10-26 23:29 UTCEG score recompute
  14. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  15. 2026-10-25 21:11 UTCEG score recompute
  16. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  17. 2026-10-25 13:56 UTCEG score recompute
  18. 2026-10-24 22:24 UTCEG score recompute
  19. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  20. 2026-10-23 23:38 UTCEG score recompute
  21. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  22. 2026-10-23 00:44 UTCEG score recompute
  23. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  24. 2026-10-22 01:52 UTCEG score recompute
  25. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
Show 68 more
  1. 2026-10-21 03:05 UTCEG score recompute
  2. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  3. 2026-10-20 04:15 UTCEG score recompute
  4. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  5. 2026-10-19 05:03 UTCEG score recompute
  6. 2026-10-18 03:06 UTCEG score recompute
  7. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  8. 2026-10-17 06:00 UTCEG score recompute
  9. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  10. 2026-10-16 07:06 UTCEG score recompute
  11. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  12. 2026-10-15 05:54 UTCEG score recompute
  13. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  14. 2026-10-14 01:31 UTCEG score recompute
  15. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  16. 2026-10-12 21:42 UTCEG score recompute
  17. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  18. 2026-10-12 14:53 UTCEG score recompute
  19. 2026-10-11 19:18 UTCEG score recompute
  20. 2026-10-11 16:35 UTCEG score recompute
  21. 2026-10-11 13:52 UTCEG score recompute
  22. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  23. 2026-10-10 21:58 UTCEG score recompute
  24. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  25. 2026-10-09 21:54 UTCEG score recompute
  26. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  27. 2026-10-08 17:30 UTCEG score recompute
  28. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  29. 2026-10-08 02:00 UTCEG score recompute
  30. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  31. 2026-10-06 16:17 UTCEG score recompute
  32. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  33. 2026-10-05 20:24 UTCEG score recompute
  34. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  35. 2026-10-05 00:34 UTCEG score recompute
  36. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  37. 2026-10-03 16:47 UTCEG score recompute
  38. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  39. 2026-10-02 20:58 UTCEG score recompute
  40. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  41. 2026-10-01 21:02 UTCEG score recompute
  42. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  43. 2026-09-30 16:50 UTCEG score recompute
  44. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  45. 2026-09-30 00:27 UTCEG score recompute
  46. 2026-09-29 16:49 UTCEG score recompute
  47. 2026-09-29 00:39 UTCEG score recompute
  48. 2026-09-28 16:43 UTCEG score recompute
  49. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  50. 2026-09-27 16:42 UTCEG score recompute
  51. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  52. 2026-09-26 16:47 UTCEG score recompute
  53. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  54. 2026-09-26 00:46 UTCEG score recompute
  55. 2026-09-24 15:44 UTCEG score recompute
  56. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  57. 2026-09-23 19:49 UTCEG score recompute
  58. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  59. 2026-09-22 16:02 UTCEG score recompute
  60. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  61. 2026-09-22 00:08 UTCEG score recompute
  62. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  63. 2026-09-20 20:20 UTCEG score recompute
  64. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  65. 2026-09-19 16:29 UTCEG score recompute
  66. 2026-09-18 16:25 UTCEG score recompute
  67. 2026-09-18 16:02 UTCEG score recomputeFirst assessed: 9.8 CRITICAL
  68. 2026-09-18 15:59 UTCMITRE cvelistV5first tracked

Publicly available exploits

(1 reference)

Public exploit code is referenced for this CVE (1 GitHub PoC). Defenders should treat patch urgency accordingly.

  • GitHub PoCdinosn/libheif-cve-2026-84383-lab
    Published Sep 29, 2026

    Docker lab for validating CVE-2026-84383 in libheif through Discourse

    Open source ↗

Frequently asked(5)

What is CVE-2026-84383?
CVE-2026-84383 is a critical-severity vulnerability; its CVE record was 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::transfer_channel_from_image_as() append duplicate Alpha planes with different bit depths to m_storage.…
When was the CVE record for CVE-2026-84383 published?
The CVE record for CVE-2026-84383 was published on September 18, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 18, 2026; the record at its source may have been updated since.
Is CVE-2026-84383 actively exploited?
CVE-2026-84383 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (53rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-84383?
CVE-2026-84383 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-84383?
A fix for CVE-2026-84383 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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