CVE-2026-86435Suited to automated attack · CISA

commonmark 1.5.0 before 2.8.4 Denial of Service via Footnote

CVSS score

8.7

EPSS probability

%0.5

Risk score

0.0

Published

1 mo ago

Overview Public Exploits (0)Newsroom Vulnerability Timeline

Patch status has not yet been verified

Resmî kaynaklarda yeterli kanıt bulunamadı. Bu sonuç “yama yok” anlamına gelmez.

Impact on My Inventory

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Vulnerability description

DayBreach CVE AI Research

CVE-2026-86435 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessive memory and CPU to exhaust server resources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-86435 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

ID	VENDOR	PRODUCT	ACTION
1	thephpleague	commonmark	View

Total affected vendors: 1|Products: 1

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCORE	VERSION	SEVERITY	VECTOR	SOURCE
8.7	CVSS V40	HIGH	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X	NVD
8.7	CVSS V4_0	HIGH	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	CVE CNA
7.5	CVSS V31	HIGH	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	NVD
7.5	CVSS V3_1	HIGH	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CVE CNA

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Confirm the affected product and version against the source evidence above.

Restrict access to internet-facing services and apply network segmentation.

Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.

Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-86435 is associated with the following CWEs:

CWE-407: Common Weakness Enumeration Entry CWE-407

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-86435 weaknesses.

CAPEC-66: SQL Injection CAPEC-126: Path Traversal CAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureAğ üzerinden

PermissionsGerekmiyor

UserGerekmiyor

Official Sources and Advisories

GitHub Security Advisory (GHSA-jfm3-95jq-q3rf)vendor-advisory VulnCheck Advisory: commonmark 1.5.0 before 2.8.4 Denial of Service via Footnotevendor-advisory

CVSS Vector Radar Chart

8.7 / 10

Vulnerability Scoring Details

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone required

User InteractionNone required

Confidentiality (Gizlilik)Low

Integrity (Bütünlük)None

Availability (Erişilebilirlik)High

Yama durumu bilinmiyor

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Follow the vendor

thephpleague

Weakness Type (CWE & CAPEC)

CWE-407

Similar Vulnerabilities

7.5

CVE-2026-71488

league/commonmark: Quadratic-time denial of service when parsing crafted Markdown

VendorthephpleagueProductcommonmark+2 etkilenen

Patch verifiedEPSS %12 mo ago

8.7

CVE-2026-86429

Get this vulnerability through the API

Affected products, version ranges, exploitation status and patch information in a single request, with a free key.

Get a free key Documentation

curl -H "x-api-key: $DAYBREACH_API_KEY" \
  "https://api.enginteksut.com.tr/api/v1/intel/cves/CVE-2026-86435"