The REXML module in Ruby 1.8.6 through 1.8.6-p287, 1.8.7 through 1.8.7-p72, and 1.9 allows context-dependent attackers to cause a denial of
The REXML module in Ruby 1.8.6 through 1.8.6-p287, 1.8.7 through 1.8.7-p72, and 1.9 allows context-dependent attackers to cause a denial of service (CPU consumption) via an XML document with recursively nested entities, aka an "XML entity explosion."
- Published
- Aug 27, 2008
- Updated
- Jun 16, 2026
- EPSS
- 15.2% · 97th percentile
- CWE
- CWE-20
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Report tools
Action score
25
Monitor
Low priority for now.
- CVSS
- 20 / 40 · 5.0 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 5 / 30 · 15.2%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| ruby-lang | ruby | cpe:2.3:a:ruby-lang:ruby |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- ruby-lang ruby1.8.6
- ruby-lang ruby1.8.7
- ruby-lang ruby1.9
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:4.0 | ruby1.8 | before 1.8.5-4etch3 | 1.8.5-4etch3 |
| Debian:4.0 | ruby1.9 | before 1.9.0+20060609-1etch3 | 1.9.0+20060609-1etch3 |
| Red Hat:enterprise_linux:4::as | irb | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:4::as | ruby | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:4::as | ruby-debuginfo | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:4::as | ruby-devel | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:4::as | ruby-docs | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:4::as | ruby-libs | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:4::as | ruby-mode | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:4::as | ruby-tcltk | before 0:1.8.1-7.el4_7.1 | 0:1.8.1-7.el4_7.1 |
| Red Hat:enterprise_linux:5::client | ruby-docs | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client | ruby-irb | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client | ruby-libs | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client | ruby-rdoc | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client | ruby-ri | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client | ruby-tcltk | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client_workstation | ruby | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client_workstation | ruby-debuginfo | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client_workstation | ruby-devel | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
| Red Hat:enterprise_linux:5::client_workstation | ruby-mode | before 0:1.8.5-5.el5_2.5 | 0:1.8.5-5.el5_2.5 |
Same product
ruby-lang: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-17405Ruby before 2.4.3 allows Net::FTP command injection.57Plan
- CVE-2008-3656Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.split_header_value function in WEBrick::HTTP::DefaultFileHandler in WEBrick i52Plan
- CVE-2021-28966In Ruby through 3.0 on Windows, a remote attacker can submit a crafted path when a Web application handles a parameter with TmpDir.47Plan
- CVE-2017-14064Ruby through 2.2.7, 2.3.x through 2.3.4, and 2.4.x through 2.4.1 can expose arbitrary memory during a JSON.generate call.42Plan
- CVE-2017-17790The lazy_initialize function in lib/resolv.rb in Ruby through 2.4.3 uses Kernel#open, which might allow Command Injection attacks, as demons41Plan
- CVE-2016-2339An exploitable heap overflow vulnerability exists in the Fiddle::Function.new "initialize" function functionality of Ruby.41Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:ruby1.8 | 1.8.5-4etch3 · Debian:4.0 | Package registry (OSV) |
| debian:ruby1.9 | 1.9.0+20060609-1etch3 · Debian:4.0 | Package registry (OSV) |
| red hat:irb | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ruby | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ruby-debuginfo | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ruby-devel | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ruby-docs | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ruby-irb | 0:1.8.5-5.el5_2.5 · Red Hat:enterprise_linux:5::client | Package registry (OSV) |
| red hat:ruby-libs | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ruby-mode | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
| red hat:ruby-rdoc | 0:1.8.5-5.el5_2.5 · Red Hat:enterprise_linux:5::client | Package registry (OSV) |
| red hat:ruby-ri | 0:1.8.5-5.el5_2.5 · Red Hat:enterprise_linux:5::client | Package registry (OSV) |
| red hat:ruby-tcltk | 0:1.8.1-7.el4_7.1 · Red Hat:enterprise_linux:4::as | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Exploit-DB entry ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Exploit-DB entry | dos | 2008-08-23 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- First PoC-5 d
- Published
- TodaySep 30, 2026+6608 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.
Technical details
Attack conditions
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- P · the service can be disrupted
- Attack complexity
- Low
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- P
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
AV:N/AC:L/Au:N/C:N/I:N/A:P
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- groups.google.com/group/comp.lang.ruby/browse_thread/thread/19f69e8a081fc0d1/e138e014b74352ca
- lists.apple.com/archives/security-announce/2009/May/msg00002.html
- secunia.com/advisories/31602
- secunia.com/advisories/32165
- secunia.com/advisories/32219
- secunia.com/advisories/32255
- secunia.com/advisories/32256
- secunia.com/advisories/32371
- secunia.com/advisories/33178
- secunia.com/advisories/33185
- secunia.com/advisories/35074
- security.gentoo.org/glsa/glsa-200812-17.xml
- support.apple.com/kb/HT3549
- support.avaya.com/elmodocs2/security/ASA-2008-424.htm
- weblog.rubyonrails.org/2008/9/3/rails-2-0-4-maintenance-release
- www.debian.org/security/2008/dsa-1651
- www.debian.org/security/2008/dsa-1652
- www.openwall.com/lists/oss-security/2008/08/25/4
- www.openwall.com/lists/oss-security/2008/08/26/1
- www.openwall.com/lists/oss-security/2008/08/26/4
Vendor advisories and official records. Exploit/PoC links are deliberately left out.