CVE-2025-66034

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.6% (48th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 6.3 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2025-12-01) is not newer than that change (2026-10-18), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Elevated

Also known asEUVD-2025-199882 (ENISA EUVD) · GHSA-768j-98cg-p3fv (GitHub Security Advisories) · PYSEC-2026-1389 (OSV.dev)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.8Exploit: Public PoCExposed services: Not assessed

A fix is available — apply it.

fontTools is a library for manipulating fonts, written in Python. In versions from 4.33.0 to before 4.60.2, the fonttools varLib (or python3 -m fontTools.varLib) script has an arbitrary file write vulnerability that leads to remote code execution when a malicious .designspace file is processed. The vulnerability affects the main() code path of fontTools.varLib, used by the fonttools varLib CLI and any code that invokes fontTools.varLib.main(). This issue has been patched in version 4.60.2.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
60
EG Risk 60/100

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.
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 public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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
0.6%
EPSS %ILE
48th
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.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). 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: 60 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 public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 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 partial (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 29, 2025

Last Modified

October 18, 2026

Advisory Details (2)

Auto-updated Nov 7, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
GitHub advisoryMentions a patch (unverified)🟡 PoC Available

Arbitrary File Write and XML injection in fontTools.varLib · Advisory · fonttools/fonttools · GitHub

https://github.com/fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fv
GitHub commit Patch Available

commit a696d5ba9327 (fonttools/fonttools)

Patch available: fonttools/fonttools 4.61.0 (contains commit a696d5ba9327)

https://github.com/fonttools/fonttools/commit/a696d5ba93270d5954f98e7cab5ddca8a02c1e32

Vendor Advisories for CVE-2025-66034(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(5)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntupython3-fonttools (4.55.3-2ubuntu0.25.04.1) @ plucky2026-11-11ubuntu
redhatrhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9:17718741812026-03-04redhat
redhatrhoai/odh-openvino-model-server-rhel9:17706214502026-02-12redhat
redhatrhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9:17700554252026-02-05redhat
pipfonttools @ 4.60.2 (fixes >= 4.33.0, < 4.60.2)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
fonttools4.19.1-1 ... 4.62.1-7 (45 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
fonttools4.38.0-1
  • every version up to 4.38.0-1+deb12u1: fixed in 4.38.0-1+deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
fonttools4.57.0-1
  • every version up to 4.57.0-1+deb13u1: fixed in 4.57.0-1+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
fonttools4.57.0-1, 4.57.0-2, 4.57.0-3
  • every version up to 4.61.1-1: fixed in 4.61.1-1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
fonttools4.33.0 ... 4.60.1 (71 versions)
  • 4.33.0 up to 4.60.2: fixed in 4.60.2
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 18× in last 7d / 73× 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.

Showing the most recent 100 of 288 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 188 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 19:15 UTCEchelonGraph re-scored
  2. 2026-11-12 19:15 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  3. 2026-11-12 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  4. 2026-11-11 20:11 UTCEchelonGraph re-scored
  5. 2026-11-11 20:11 UTCVendor advisory
  6. 2026-11-11 20:11 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  7. 2026-11-11 16:36 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  8. 2026-11-10 21:07 UTCEchelonGraph re-scored
  9. 2026-11-10 21:07 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  10. 2026-11-10 16:41 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  11. 2026-11-09 21:55 UTCEchelonGraph re-scored
  12. 2026-11-09 21:55 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  13. 2026-11-09 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  14. 2026-11-08 22:53 UTCEchelonGraph re-scored
  15. 2026-11-08 22:53 UTCVendor advisory
  16. 2026-11-08 22:53 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  17. 2026-11-08 16:37 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  18. 2026-11-07 23:51 UTCEchelonGraph re-scored
  19. 2026-11-07 23:51 UTCVendor advisory
  20. 2026-11-07 23:51 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  21. 2026-11-07 16:37 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  22. 2026-11-07 00:48 UTCEchelonGraph re-scored
  23. 2026-11-07 00:48 UTCVendor advisory
  24. 2026-11-07 00:48 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  25. 2026-11-06 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
Show 75 more
  1. 2026-11-06 01:46 UTCEchelonGraph re-scored
  2. 2026-11-06 01:46 UTCVendor advisory
  3. 2026-11-06 01:46 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  4. 2026-11-05 17:55 UTCOSV refresh
  5. 2026-11-05 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  6. 2026-11-05 02:44 UTCEchelonGraph re-scored
  7. 2026-11-05 02:44 UTCVendor advisory
  8. 2026-11-05 02:44 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  9. 2026-11-04 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  10. 2026-11-04 03:41 UTCEchelonGraph re-scored
  11. 2026-11-04 03:41 UTCVendor advisory
  12. 2026-11-04 03:41 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  13. 2026-11-03 16:45 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  14. 2026-11-03 04:39 UTCEchelonGraph re-scored
  15. 2026-11-03 04:39 UTCVendor advisory
  16. 2026-11-03 04:39 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  17. 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  18. 2026-11-02 05:29 UTCEchelonGraph re-scored
  19. 2026-11-02 05:29 UTCVendor advisory
  20. 2026-11-02 05:29 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  21. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  22. 2026-11-01 08:02 UTCGHSA enrichmentGHSA-768j-98cg-p3fv · GitHub severity MODERATE · GitHub CVSS 6.3
  23. 2026-11-01 08:02 UTCEchelonGraph re-scored
  24. 2026-11-01 06:26 UTCEchelonGraph re-scored
  25. 2026-11-01 06:26 UTCVendor advisory
  26. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  27. 2026-10-31 07:24 UTCEchelonGraph re-scored
  28. 2026-10-31 07:24 UTCVendor advisory
  29. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  30. 2026-10-30 08:21 UTCEchelonGraph re-scored
  31. 2026-10-30 08:21 UTCVendor advisory
  32. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  33. 2026-10-29 09:19 UTCEchelonGraph re-scored
  34. 2026-10-29 09:19 UTCVendor advisory
  35. 2026-10-28 16:30 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  36. 2026-10-28 10:17 UTCEchelonGraph re-scored
  37. 2026-10-28 10:17 UTCVendor advisory
  38. 2026-10-27 16:30 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  39. 2026-10-27 10:18 UTCEchelonGraph re-scored
  40. 2026-10-27 10:18 UTCVendor advisory
  41. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  42. 2026-10-26 11:16 UTCEchelonGraph re-scored
  43. 2026-10-26 11:16 UTCVendor advisory
  44. 2026-10-25 16:31 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  45. 2026-10-25 16:09 UTCEchelonGraph re-scored
  46. 2026-10-25 12:14 UTCEchelonGraph re-scored
  47. 2026-10-25 12:14 UTCVendor advisory
  48. 2026-10-24 16:31 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  49. 2026-10-24 13:07 UTCEchelonGraph re-scored
  50. 2026-10-24 13:07 UTCVendor advisory
  51. 2026-10-23 16:30 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  52. 2026-10-23 14:00 UTCEchelonGraph re-scored
  53. 2026-10-23 14:00 UTCVendor advisory
  54. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  55. 2026-10-22 14:54 UTCEchelonGraph re-scored
  56. 2026-10-22 14:54 UTCVendor advisory
  57. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  58. 2026-10-21 15:49 UTCVendor advisory
  59. 2026-10-20 16:42 UTCEchelonGraph re-scored
  60. 2026-10-20 16:42 UTCVendor advisory
  61. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  62. 2026-10-19 17:38 UTCEchelonGraph re-scored
  63. 2026-10-19 17:38 UTCVendor advisory
  64. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  65. 2026-10-18 18:27 UTCVendor advisory
  66. 2026-10-18 17:24 UTCEchelonGraph re-scored
  67. 2026-10-18 17:24 UTCVendor advisory
  68. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  69. 2026-10-18 05:19 UTCEchelonGraph re-scored
  70. 2026-10-17 18:22 UTCEchelonGraph re-scored
  71. 2026-10-17 18:22 UTCVendor advisory
  72. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  73. 2026-10-16 19:19 UTCEchelonGraph re-scored
  74. 2026-10-16 19:19 UTCVendor advisory
  75. 2026-10-16 16:39 UTCEPSS rescoreEPSS 0.5% · 44th percentile

Publicly available exploits

(4 references)

Public exploit code is referenced for this CVE (4 GitHub PoCs). Defenders should treat patch urgency accordingly.

  • GitHub PoCv3cn4x00/POC-CVE-2025-66034
    Published Mar 21, 2026
    Open source ↗
  • GitHub PoCLiquid1998/Variatype.htb-CVE-2025-66034
    Published Mar 16, 2026
    Open source ↗
  • GitHub PoCLiquid-Sec/Variatype.htb-CVE-2025-66034
    Published Mar 16, 2026
    Open source ↗
  • GitHub PoCsymphony2colour/varlib-cve-2025-66034
    Published Mar 15, 2026

    Proof-of-concept exploit for CVE-2025-66034 in the fontTools variable font generation pipeline. A crafted .designspace file allows control of the output path, enabling arbitrary file writes. The script automates payload creation, font generation, and upload to demonstrate the issue.

    Open source ↗

Related CVEs(same product + same vendor + same CWE)

Same product

1 shown

Debian:12:fonttools

Frequently asked(5)

What is CVE-2025-66034?
CVE-2025-66034 is a critical-severity vulnerability; its CVE record was published on November 29, 2025. fontTools is a library for manipulating fonts, written in Python. In versions from 4.33.0 to before 4.60.2, the fonttools varLib (or python3 -m fontTools.varLib) script has an arbitrary file write vulnerability that leads to remote code execution when a malicious .designspace file is processed. The…
When was the CVE record for CVE-2025-66034 published?
The CVE record for CVE-2025-66034 was published on November 29, 2025. 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 October 18, 2026; the record at its source may have been updated since.
Is CVE-2025-66034 actively exploited?
CVE-2025-66034 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (48th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2025-66034?
CVE-2025-66034 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2025-66034?
A fix for CVE-2025-66034 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2025-66034 are linked in the Vendor Advisories panel on this page.

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