Home/CVE/In Secure Headers (RubyGem secure_headers), a directive injection vulnerability is present in versions before 3.8.0, 5.1
CVE
CVE-2020-52173
In Secure Headers (RubyGem secure_headers), a directive injection vulnerability is present in versions before 3.8.0, 5.1
In Secure Headers (RubyGem secure_headers), a directive injection vulnerability is present in versions before 3.8.0, 5.1.0, and 6.2.0. If user-supplied input was passed into append/override_content_security_policy_directives, a semicolon could be injected leading to directive injection. This could be used to e.g. override a script-src directive.
Duplicate directives are ignored and the first one wins. The directives in secure_headers are sorted alphabetically so they pretty much all come before script-src. A previously undefined directive would receive a value even if SecureHeaders::OPT_OUT was supplied.
The fixed versions will silently convert the semicolons to spaces and emit a deprecation warning when this happens. This will result in innocuous browser console messages if being exploited/accidentally used. In future releases, we will raise application errors resulting in 500s.
Depending on what major version you are using, the fixed versions are 6.2.0, 5.1.0, 3.8.0.
MEDIUM · CVSS 4.4
EPSS 0.01814
EPSS exploitation odds1.81% · top 24%
Schedule remediation
- Public exploit or PoC is available
No Sigma yet — build one →
YARA rules0
Look this up elsewhere - one-click external pivots
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How to read a CVE - triage first, then detect and patch
This page is every public fact about CVE-2020-5217, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.
Triage: should I act now? Four signals, and they are not interchangeable:
CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked.
EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal.
CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score.
Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.
How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.
Then what - two workflows:
Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits.
PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.
Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).
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Exploitation evidence
1 of 7 sources
Corroboration score 8/100 ·
emerging.
This counts how many independent sources have exploitation evidence, and separates two different things:
confirmed in-the-wild use (CISA KEV, Microsoft MSRC, ransomware activity) from
exploit / PoC availability (Metasploit, ExploitDB, Nuclei, public PoCs). A template or PoC existing means
an attack is possible and easy - it is not, on its own, proof the CVE is being exploited in the wild.
Exploit / PoC available
public PoC
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Exploitation momentum
413 days of EPSSdormant
Flat and low - no real exploitation pressure. This reads the direction and speed of EPSS over time, which can move before EPSS itself peaks or before CISA lists it.
EPSS exploitation probability
1.81%
Top 24%odds of exploitation in the next 30 days
CVSS metric silhouette
shape grows toward worst-case
SSVC triage
No SSVC vulnrichment for this CVE. CISA's Vulnrichment program scores newer CVEs (~2024 onwards) plus selected older critical ones. Use the EPSS probability + KEV status to triage instead.
CVSS vector breakdown
Exploitability - how they get in
Attack Vector
Network
Adjacent
Local
Physical
Attack Complexity
Low
High
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Impact - what breaks
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
VECTOR
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:NLifecycle
- 23 Jan 2020Published to NVD
- 17 Jun 2026Last modified
Every entry is a recorded date - NVD publish/modify, CISA KEV add, public exploit disclosure. No inferred events.
Attack path
Full kill chain
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Public Exploits & PoCs
3These PoC and exploit links come from public sources and are not verified to be safe or functional. Review the code before running anything, and treat unverified entries as untrusted. Signed-in users mark whether it works, rate 1-10, and can report malware with a required reason that becomes a public comment.
Source
Works?
no reports yet
Rating
Works?
no reports yet
Rating
Works?
no reports yet
Rating
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ATT&CK techniques
5Techniques this CVE enables. Pills with a solid outline are high confidence - named directly in ATT&CK or Nuclei, or human-curated by CTID; the rest are inferred from the weakness type using MITRE's CVE Mapping Methodology and the CWE → CAPEC chain. Broad, generic-weakness guesses are filtered out. A small N× marks a technique that N independent sources agree on.
T1059 · Command and Scripting Interpreter T1185 · Browser Session Hijacking T1027.006 · HTML Smuggling T1027.009 · Embedded Payloads T1564.009 · Resource Forking
▤ Build a SIEM detection for these techniques
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CAPEC attack patterns
12Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.
CAPEC-CAPEC-10 · Buffer Overflow via Environment Variables CAPEC-CAPEC-101 · Server Side Include (SSI) Injection CAPEC-CAPEC-105 · HTTP Request Splitting CAPEC-CAPEC-108 · Command Line Execution through SQL Injection CAPEC-CAPEC-120 · Double Encoding CAPEC-CAPEC-13 · Subverting Environment Variable Values CAPEC-CAPEC-135 · Format String Injection CAPEC-CAPEC-14 · Client-side Injection-induced Buffer Overflow CAPEC-CAPEC-24 · Filter Failure through Buffer Overflow CAPEC-CAPEC-250 · XML Injection CAPEC-CAPEC-267 · Leverage Alternate Encoding CAPEC-CAPEC-273 · HTTP Response Smuggling
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Weakness Classification
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Affected Products & Versions
3twitter secure headers< 3.8.0
twitter secure headers>= 5.0.0 and < 5.1.0
twitter secure headers>= 6.0.0 and < 6.2.0
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Affected Packages
1Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
RubyGems
secure_headers
MODERATE
fixed in 6.2.0
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Related CVEs
8CVEs linked to this one by a shared weakness (CWE) or affected product - joins on data already in the engine, with the reason shown per row.
CVE-2004-2570
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same CWE-74
CVE-2004-1157
Opera 7.x up to 7.54, and possibly other versions, allows remote attackers to sp...
same CWE-74
CVE-2005-3007
Opera before 8.50 allows remote attackers to spoof the content type of files via...
same CWE-74
CVE-2005-3750
Opera before 8.51 on Linux and Unix systems allows remote attackers to execute a...
same CWE-74
CVE-2011-10033
The WordPress plugin is-human <= v1.4.2 contains an eval injection vulnerabili...
same CWE-95
CVE-2013-10051
A remote PHP code execution vulnerability exists in InstantCMS version 1.6 and e...
same CWE-95
CRITICAL
CVE-2013-10070
PHP-Charts v1.0 contains a PHP code execution vulnerability in wizard/url.php, w...
same CWE-95
CVE-2019-9507
The web interface of the Vertiv Avocent UMG-4000 version 4.2.1.19 is vulnerable ...
same CWE-95
HIGH
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Vendor Advisories
1🔗
References & Sources
3Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.