CVE Intelligence
High Memory corruption

CVE-2026-102941 — gomarkdown/markdown IsSafeURL panics on short URLs

The package github.com/gomarkdown/markdown is a Go library for parsing Markdown text and rendering as HTML. Prior to 0.0.0-20260724235538-61af6e1e6971, parser.IsSafeURL in parser/parser.go slices url[:nPath] before the len(url) >= nPath guard. A short destination causes a slice-bounds panic when the loop reaches a relative-path prefix for which len(url) < nPath and cap(url) < nPath. The one-byte destination / is an explicit non-panic counterexample because it matches the first valid path and returns before a longer prefix is sliced. Demonstrated panic cases include empty, ., and .. destinations under those conditions. The panic is reachable when markdown.ToHTML renders untrusted Markdown with html.Safelink enabled, including an empty link destination, and is also reachable by callers that pass a short attacker-controlled URL directly to the exported parser.IsSafeURL function. An uncaught panic can terminate the calling process and cause denial of service. This issue is fixed in 0.0.0-20260724235538-61af6e1e6971.

Published Oct 16, 2026 · Updated Oct 16, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: GitHub_M

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
—
No EPSS score.
Affects
Gomarkdown
Markdown and 1 more
CVSS base
7.5
High · 3 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Go Github.com/gomarkdown/markdown: fixed in version 0.0.0-20260724235538-61af6e1e6971 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Gomarkdown Markdown, Go Github.com/gomarkdown/markdown).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Gomarkdown Markdown version < 0.0.0-20260724235538-61af6e1e6971 Vulnerable CVE Program (cve.org) e CISA ADP
Go Github.com/gomarkdown/markdown < 0.0.0-20260724235538-61af6e1e6971 Vulnerable GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.5 CVSS 3.1 High 3.9 3.6 security-advisories@github.com via NIST National Vulnerability Database
7.5 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
7.5 CVSS 3.1 High — — GitHub_M via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-125 · Out-of-bounds Read

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 16, 2026 · GitHub Security Advisories
  • Affected products added · go/github.com/gomarkdown/markdown
    Oct 16, 2026 · GitHub Security Advisories
  • Source status changed · Received → Deferred
    Oct 16, 2026 · NIST National Vulnerability Database
  • Source status changed · Published → Received
    Oct 16, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 16, 2026
  • CVSS changed · 7.5
    Oct 16, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 16, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 16, 2026 · CVE Program (cve.org) e CISA ADP
  • CVE published
    Oct 16, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 16, 2026 – Oct 16, 2026
  • 1× Official description updated · Oct 16, 2026 – Oct 16, 2026

References

3 on the record

Elsewhere on this site

Gomarkdown
every CVE for this vendor
Memory corruption
same class
CWE-125
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-40890 github.com/gomarkdown/markdown: Out-of-bounds Read in SmartypantsRenderer Apr 21, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No FIRST EPSS score.
  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-102941 is "gomarkdown/markdown IsSafeURL panics on short URLs", rated High. It affects Markdown (Gomarkdown); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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