CVE-2026-63660

HIGHPre-NVD 8.18.1
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (35th 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

Also known asEUVD-2026-123100 (ENISA EUVD)Source: ENISA EUVD

8.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 8.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

node-fontnik is a library that delivers a range of glyphs rendered as SDFs (signed distance fields) in a protocol buffer. Prior to version 0.7.7, a crafted font could trigger a heap out-of-bounds write in RenderSDF (include/mapbox/glyph_foundry_impl.hpp). RenderSDF computed the SDF bitmap allocation size as buffered_width * buffered_height in 32-bit unsigned int. Glyph dimensions are derived from the uploaded font's outline bounding box with no upper bound, so a glyph large enough to make that product exceed 2³² wrapped to a small value. The buffer was then under-allocated while the render loop still wrote one byte per pixel, corrupting the heap (CWE-190 → CWE-787) and crashing the process. A 680-byte font is enough to drive FreeType to a 65536×65536 buffered glyph, wrapping the size to 0. This issue has been patched in version 0.7.7.

CVSS v3
8.1
EG Score
8.1HIGHmedium confidence
EG Risk
37
EG Risk 37/100

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)
Severity81% × 45%
Impact severity (EG Severity): CVSS 8.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
0.4%
EPSS %ILE
35th
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 (8.1): severity, escalated by confirmed exploitation. This CVE's 8.1 is its impact severity (EG Severity), not escalated.

EG Severity
8.1 HIGHCVSS-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
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-13). 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 or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade 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 or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (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

November 11, 2026

Last Modified

November 13, 2026

Advisory Details (3)

Auto-updated Nov 11, 2026
Patch available. Sources: github, github_pr, github_release.
GitHub release Patch Available

v0.7.7

Patch available: mapbox/node-fontnik v0.7.7

https://github.com/mapbox/node-fontnik/releases/tag/v0.7.7
GitHub pull request Patch Available

Fix integer-overflow heap out-of-bounds write in RenderSDF

Patch available: mapbox/node-fontnik v0.7.7 (PR #202 merged 2026-07-02)

https://github.com/mapbox/node-fontnik/pull/202
GitHub advisoryMentions a patch (unverified)

Fix integer-overflow heap out-of-bounds write in RenderSDF · Advisory · mapbox/node-fontnik · GitHub

https://github.com/mapbox/node-fontnik/security/advisories/GHSA-cfm6-c7rv-58xj

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 5× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

  1. 2026-11-13 17:29 UTCEchelonGraph re-scored
  2. 2026-11-13 17:14 UTCEchelonGraph re-scored
  3. 2026-11-13 16:53 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  4. 2026-11-12 22:29 UTCEchelonGraph re-scored
  5. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  6. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  7. 2026-11-11 04:00 UTCENISA EUVD ID recordedEUVD-2026-123100 · Source: ENISA EUVD
  8. 2026-11-11 03:28 UTCEchelonGraph re-scored
  9. 2026-11-11 02:50 UTCEchelonGraph re-scoredFirst assessed: 8.1 HIGH
  10. 2026-11-11 02:49 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-63660?
CVE-2026-63660 is a high-severity vulnerability; its CVE record was published on November 11, 2026. node-fontnik is a library that delivers a range of glyphs rendered as SDFs (signed distance fields) in a protocol buffer. Prior to version 0.7.7, a crafted font could trigger a heap out-of-bounds write in RenderSDF (include/mapbox/glyph_foundry_impl.hpp). RenderSDF computed the SDF bitmap…
When was the CVE record for CVE-2026-63660 published?
The CVE record for CVE-2026-63660 was published on November 11, 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 November 13, 2026; the record at its source may have been updated since.
Is CVE-2026-63660 actively exploited?
CVE-2026-63660 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (35th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63660?
CVE-2026-63660 has a CVSS base score of 8.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63660?
A fix for CVE-2026-63660 is available: update to the fixed version the vendor names in its advisory.

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