CVE Intelligence
Medium Injection

CVE-2020-26247 — XXE in Nokogiri

Nokogiri is a Rubygem providing HTML, XML, SAX, and Reader parsers with XPath and CSS selector support. In Nokogiri before version 1.11.0.rc4 there is an XXE vulnerability. XML Schemas parsed by Nokogiri::XML::Schema are trusted by default, allowing external resources to be accessed over the network, potentially enabling XXE or SSRF attacks. This behavior is counter to the security policy followed by Nokogiri maintainers, which is to treat all input as untrusted by default whenever possible. This is fixed in Nokogiri version 1.11.0.rc4.

Published Dec 30, 2020 · Updated Oct 25, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, 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
  • EPSS 1.2% (30-day exploitation probability)+10
  • Technical severity (medium)+3

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
1.18%
ahead of 68% of scored CVEs · Oct 25, 2026
Affects
Debian
Debian Linux and 1 more
CVSS base
4.3
Medium · 4 source(s)

Remediation

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

  • Documented patch — github.com (NIST National Vulnerability Database)
  • Documented mitigation — github.com (NIST National Vulnerability Database)
  • Rubygems Nokogiri: fixed in version 1.11.0 — 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 (Debian Debian Linux, Nokogiri Nokogiri, Sparklemotion Nokogiri…).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Debian Debian Linux version 9.0version 10.0 Vulnerable NIST National Vulnerability Database
Nokogiri Nokogiri < 1.11.0version 1.11.0-rc1version 1.11.0-rc2version 1.11.0-rc3 Vulnerable NIST National Vulnerability Database
Sparklemotion Nokogiri version < 1.11.0.rc4 Vulnerable CVE Program (cve.org) e CISA ADP
Rubygems Nokogiri ≤ 1.10.10 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
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

Every base score collected

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

ScoreVersionSeverityExpl.ImpactScored by
4.3 CVSS 3.1 Medium 2.8 1.4 nvd@nist.gov via NIST National Vulnerability Database
4.3 CVSS 3.1 Medium — — GitHub, Inc. via GitHub Security Advisories
2.6 CVSS 3.1 Low 1.2 1.4 security-advisories@github.com via NIST National Vulnerability Database
2.6 CVSS 3.1 Low — — GitHub_M via CVE Program (cve.org) e CISA ADP
4.0 CVSS 2.0 Medium 8.0 2.9 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 4.3 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-611 · XML External Entity (XXE)

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).
  • Look for parameters with command/query metacharacters and unexpected child processes of the service.
web/proxy/WAF logsnetwork IDS/IPSapplication logsendpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 25, 2026 · GitHub Security Advisories
  • Affected products added · rubygems/nokogiri
    Oct 25, 2026 · GitHub Security Advisories
  • Affected products added · sparklemotion/nokogiri
    Oct 25, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 25, 2026
  • Fix documented
    Oct 25, 2026 · NIST National Vulnerability Database
  • Affected products added · nokogiri/nokogiri, debian/debian linux
    Oct 25, 2026 · NIST National Vulnerability Database
  • CVSS changed · 4.3
    Oct 25, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 25, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 25, 2026 · Alertas do Telegram
  • 2020
  • CVE published
    Dec 30, 2020 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 25, 2026 – Oct 25, 2026
  • 1× Official description updated · Oct 25, 2026 – Oct 25, 2026

References

12 on the record

Elsewhere on this site

Debian
every CVE for this vendor
Injection
same class
CWE-611
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-79770 Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer Aug 25, 2026
  • CVE-2026-79771 Nokogiri before 1.19.3 Memory Leak via XSLT Transform Aug 25, 2026
  • CVE-2026-79772 Nokogiri before 1.19.1 Unchecked Return Value canonicalize Aug 25, 2026
  • CVE-2026-79769 Nokogiri before 1.19.4 Invalid Memory Read via initialize_copy_with_args Aug 25, 2026
  • CVE-2026-12996 A use-after-free in OpenVPN 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 allows remote... Jul 30, 2026
  • CVE-2026-14355 ext/openssl: Memory corruption in openssl_encrypt with AES-WRAP-PAD Jul 3, 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 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-2020-26247 is "XXE in Nokogiri", rated Medium. It affects Debian Linux (Debian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.3 describes technical severity. EPSS 1.18% estimates the probability of exploitation in 30 days; neither replaces your asset context. 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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