Apache HTTP Server: security vulnerability (CVE-2020-9490)
Published Sources: CVE.org, OSV
What is affected, what to do
Apache HTTP Server versions 2.4.20 to 2.4.43. A specially crafted value for the 'Cache-Digest' header in a HTTP/2 request would result in a crash when the server actually tries to HTTP/2 PUSH a resource afterwards.
An exploit is publicly available. Update http_server to version 2.4.46.
- Affected
- Apache HTTP Server
eq 2.4.20 to 2.4.43..2.4.20 to 2.4.43
- Apache HTTP Server
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
7.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
7.5
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org, OSV
88.8 %
EPSS score
High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
Source: FIRST EPSS, percentile 99.78
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 117.15 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- PoC (publicly reported)
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 7.5 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 7.5
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 88.8 %
- High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 99.78
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Apache HTTP Server versions 2.4.20 to 2.4.43. A specially crafted value for the 'Cache-Digest' header in a HTTP/2 request would result in a crash when the server actually tries to HTTP/2 PUSH a resource afterwards. Configuring the HTTP/2 feature via "H2Push off" will mitigate this vulnerability for unpatched servers.
Source: NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| — | Apache HTTP Server |
|
|
| apache | http_server |
|
|
| oracle | communications_element_manager |
|
|
| oracle | communications_session_report_manager |
|
|
| oracle | communications_session_route_manager |
|
|
| oracle | enterprise_manager_ops_center |
|
|
| oracle | hyperion_infrastructure_technology |
|
|
| oracle | instantis_enterprisetrack |
|
|
| oracle | zfs_storage_appliance_kit |
|
|
| redhat | openstack |
|
|
| redhat | openstack_for_ibm_power |
|
|
| redhat | software_collections |
|
|
Distribution and container packages (1)
Downstream packages (e.g. Bitnami, Debian, Ubuntu, Red Hat). Versions refer to the distribution, not the vendor.
| Affected versions | Fixed in | ||
|---|---|---|---|
| bitnami | apache |
|
|
Vendors and products
- Apache Software Foundation Apache HTTP Server
- Canonical Canonical Ubuntu Linux
- Debian Debian Linux
- Fedora Project Infrastructure Fedora
- openSUSE openSUSE Leap
- Oracle Communications Element Manager
- Oracle Communications Session Report Manager
- Oracle Communications Session Route Manager
- Oracle Oracle Enterprise Manager Ops Center
- Oracle Oracle Hyperion Infrastructure Technology
- Oracle Oracle Instantis EnterpriseTrack
- Oracle Oracle ZFS Storage Appliance Kit
Affected operating systems
| Linux | debian | debian_linux | 10.0 |
| Linux | redhat | enterprise_linux | 8.0 |
| Linux | redhat | enterprise_linux_eus | 8.1 |
| Linux | redhat | enterprise_linux_eus | 8.2 |
| Linux | redhat | enterprise_linux_eus | 8.4 |
| Linux | redhat | enterprise_linux_eus | 8.6 |
| Linux | redhat | enterprise_linux_for_ibm_z_systems | 8.0 |
| Linux | redhat | enterprise_linux_for_ibm_z_systems_eus | 8.1 |
| Linux | redhat | enterprise_linux_for_ibm_z_systems_eus | 8.2 |
| Linux | redhat | enterprise_linux_for_ibm_z_systems_eus | 8.4 |
| Linux | redhat | enterprise_linux_for_ibm_z_systems_eus | 8.6 |
| Linux | redhat | enterprise_linux_for_power_little_endian | 8.0 |
| Linux | redhat | enterprise_linux_for_power_little_endian_eus | 8.1 |
| Linux | redhat | enterprise_linux_for_power_little_endian_eus | 8.2 |
| Linux | redhat | enterprise_linux_for_power_little_endian_eus | 8.4 |
| Linux | redhat | enterprise_linux_for_power_little_endian_eus | 8.6 |
| Linux | redhat | enterprise_linux_server_aus | 8.2 |
| Linux | redhat | enterprise_linux_server_aus | 8.4 |
| Linux | redhat | enterprise_linux_server_aus | 8.6 |
| Linux | redhat | enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions | 8.1 |
| Linux | redhat | enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions | 8.2 |
| Linux | redhat | enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions | 8.4 |
| Linux | redhat | enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions | 8.6 |
| Linux | redhat | enterprise_linux_server_tus | 8.2 |
Public exploit references
Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.
| Packet Storm | Apache 2.4.43 mod_http2 Memory Corruption (opens in a new tab)packetstormsecurity.com | PoC (publicly reported)reported, not verified | — |
References & sources
- lists.opensuse.orgopenSUSE-SU-2020:1285web, Vendor advisory, x_refsource_SUSE, Mailing list, Third-party advisory
- lists.opensuse.orgopenSUSE-SU-2020:1293web, Vendor advisory, x_refsource_SUSE, Mailing list, Third-party advisory
- lists.opensuse.orgopenSUSE-SU-2020:1792web, Vendor advisory, x_refsource_SUSE, Mailing list, Third-party advisory
- packetstormsecurity.comfiles/160392/Apache-2.4.43-mod_http2-Memory-Corruption.htmlweb, x_refsource_MISC, Third-party advisory, Vulnerability database
- httpd.apache.orgsecurity/vulnerabilities_24.htmlweb, x_refsource_MISC, Vendor advisory
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1073143 [3/3] - in /websites/staging/httpd/trunk/content: ./ security/web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1888194 [13/13] - /httpd/site/trunk/content/security/json/web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210407 svn commit: r1888469 - /httpd/site/trunk/content/security/json/CVE-2020-9490.jsonweb, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1073149 [13/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-dev] 20200811 Which version fixed the CVE-2020-9490, CVE-2020-11984 and CVE-2020-11993 vulnerabilities?web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-dev] 20200811 Re: Which version fixed the CVE-2020-9490, CVE-2020-11984 and CVE-2020-11993 vulnerabilities?web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210606 svn commit: r1075470 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2020-13938.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlweb, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1888203 - /httpd/site/trunk/content/security/json/CVE-2020-9490.jsonweb, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210407 svn commit: r1073454 - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2020-9490.json security/vulnerabilities_24.htmlweb, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-dev] 20200808 Security announcements for CVE-2020-9490/CVE-2020-11993 ?web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1073149 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1073148 - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2020-9490.jsonweb, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1073140 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlweb, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1073139 [13/13] - in /websites/staging/httpd/trunk/content: ./ security/json/web, Mailing list, x_refsource_MLIST
- lists.apache.org[httpd-cvs] 20210330 svn commit: r1073139 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/json/web, Mailing list, x_refsource_MLIST
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<a href="https://intel.neosec.eu/en/cve/CVE-2020-9490"><img src="https://intel.neosec.eu/badge/cve/CVE-2020-9490.svg?lang=en" alt="CVE-2020-9490 – NEOSEC Intel" height="20"></a>