# What is CVE-2020-9490?

> CVE-2020-9490 is a high-severity flaw (CVSS 7.5) in HTTP Server from Apache, published on 7 August 2020. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 89%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2020-9490

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 71 out of 100 (High); action: Patch now. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.5 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 89% (latest exploit-likelihood forecast)
- **Published:** 7 August 2020
- **Record last updated:** 7 November 2023
- **Main product:** HTTP Server from Apache
- **Affected products:** 25

## What is CVE-2020-9490? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### The official 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.

### What kind of flaw is it?

- CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can take it offline

Severity vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`

## Is CVE-2020-9490 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 89%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 89%, 89%, 89%, 89%, 89%, 89%, 89%.

### Timeline

- 7 August 2020: Published
- 7 November 2023: Record last updated
- 16 June 2026: Exploit likelihood jumped

### How Precursor Intelligence ranks it

CVE-2020-9490 scores **71 out of 100 (High)**, with the action "Patch now".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2020-9490?

The published record lists 25 products. Versions are as published: "2.4.20 to before 2.4.46" means from 2.4.20 up to, but not including, 2.4.46.

- [HTTP Server](https://www.precursorintelligence.com/product/apache/http_server) by [Apache](https://www.precursorintelligence.com/vendors/apache) (Application): 2.4.20 to before 2.4.46
- [Enterprise Linux](https://www.precursorintelligence.com/product/redhat/enterprise_linux) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 6.0, 7.0, 7.6, 7.7, 8.0
- [Enterprise Linux Eus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_eus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.1, 8.2, 8.4, 8.6
- [Enterprise Linux for Ibm Z Systems Eus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_ibm_z_systems_eus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.1, 8.2, 8.4, 8.6
- [Enterprise Linux for Power Little Endian Eus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_power_little_endian_eus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.1, 8.2, 8.4, 8.6
- [Enterprise Linux Server for Power Little Endian Update Services for Sap Solutions](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.1, 8.2, 8.4, 8.6
- [Enterprise Linux Server Update Services for Sap Solutions](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_update_services_for_sap_solutions) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.1, 8.2, 8.4, 8.6
- [Enterprise Linux Server Aus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_aus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.2, 8.4, 8.6
- [Enterprise Linux Server Tus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_tus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.2, 8.4, 8.6
- [Instantis Enterprisetrack](https://www.precursorintelligence.com/product/oracle/instantis_enterprisetrack) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 17.1, 17.2, 17.3
- [Ubuntu Linux](https://www.precursorintelligence.com/product/canonical/ubuntu_linux) by [Canonical](https://www.precursorintelligence.com/vendors/canonical) (Operating system): 16.04, 18.04, 20.04
- [Fedora](https://www.precursorintelligence.com/product/fedoraproject/fedora) by [Fedoraproject](https://www.precursorintelligence.com/vendors/fedoraproject) (Operating system): 31, 32
- [Leap](https://www.precursorintelligence.com/product/opensuse/leap) by [Opensuse](https://www.precursorintelligence.com/vendors/opensuse) (Operating system): 15.1, 15.2
- [Communications Element Manager](https://www.precursorintelligence.com/product/oracle/communications_element_manager) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 8.2.0 to 8.2.2
- [Communications Session Report Manager](https://www.precursorintelligence.com/product/oracle/communications_session_report_manager) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 8.2.0 to 8.2.2
- [Communications Session Route Manager](https://www.precursorintelligence.com/product/oracle/communications_session_route_manager) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 8.2.0 to 8.2.2
- [Debian Linux](https://www.precursorintelligence.com/product/debian/debian_linux) by [Debian](https://www.precursorintelligence.com/vendors/debian) (Operating system): 10.0
- [Enterprise Linux for Ibm Z Systems](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_ibm_z_systems) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.0
- [Enterprise Linux for Power Little Endian](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_power_little_endian) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.0
- [Enterprise Manager Ops Center](https://www.precursorintelligence.com/product/oracle/enterprise_manager_ops_center) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 12.4.0.0
- [Hyperion Infrastructure Technology](https://www.precursorintelligence.com/product/oracle/hyperion_infrastructure_technology) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 11.1.2.4
- [Openstack](https://www.precursorintelligence.com/product/redhat/openstack) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Application): 16.1
- [Openstack for Ibm Power](https://www.precursorintelligence.com/product/redhat/openstack_for_ibm_power) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Application): 16.1
- [Software Collections](https://www.precursorintelligence.com/product/redhat/software_collections) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Application): 1.0
- [Zfs Storage Appliance Kit](https://www.precursorintelligence.com/product/oracle/zfs_storage_appliance_kit) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 8.8

## How do I fix CVE-2020-9490?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [oracle.com](https://www.oracle.com/security-alerts/cpujan2021.html) (Patch, Third-party advisory)
- [oracle.com](https://www.oracle.com/security-alerts/cpuoct2020.html) (Patch, Third-party advisory)
- [httpd.apache.org](https://httpd.apache.org/security/vulnerabilities_24.html#CVE-2020-9490) (Vendor advisory)
- [lists.opensuse.org](http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00068.html) (Mailing list, Third-party advisory)
- [lists.opensuse.org](http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00071.html) (Mailing list, Third-party advisory)
- [lists.opensuse.org](http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00081.html) (Mailing list, Third-party advisory)
- [packetstormsecurity.com](http://packetstormsecurity.com/files/160392/Apache-2.4.43-mod_http2-Memory-Corruption.html) (Third-party advisory, Vulnerability database)
- [lists.apache.org](https://lists.apache.org/thread.html/r06f0d87ebb6d59ed8379633f36f72f5b1f79cadfda72ede0830b42cf%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r09bb998baee74a2c316446bd1a41ae7f8d7049d09d9ff991471e8775%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r0b6541c5fb2f8fb383861333400add7def625bc993300300de0b4f8d%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r3c5c3104813c1c5508b55564b66546933079250a46ce50eee90b2e36%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r5debe8f82728a00a4a68bc904dd6c35423bdfc8d601cfb4579f38bf1%40%3Cdev.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r623de9b2b2433a87f3f3a15900419fc9c00c77b26936dfea4060f672%40%3Cdev.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r97d0faab6ed8fd0d439234b16d05d77b22a07b0c4817e7b3cca419cc%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r9e485ce5a01c9dc3d4d785a7d28aa7400ead1e81884034ff1f03cfee%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r9e9f1a7609760f0f80562eaaec2aa3c32d525c3e0fca98b475240c71%40%3Cdev.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/ra4da876037477c06f2677d7a1e10b5a8613000fca99c813958070fe9%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/rdf3e5d0a5f5c3d90d6013bccc6c4d5af59cf1f8c8dea5d9a283d13ce%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/rfed9fea918e090383da33e393eb6c2755fccf05032bd7d6eb4737c9e%40%3Ccvs.httpd.apache.org%3E)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4NKWG2EXAQQB6LMLATKZ7KLSRGCSHVAN/)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ITVFDBVM6E3JF3O7RYLRPRCH3RDRHJJY/)
- [security.gentoo.org](https://security.gentoo.org/glsa/202008-04) (Third-party advisory)
- [security.netapp.com](https://security.netapp.com/advisory/ntap-20200814-0005/) (Third-party advisory)
- [usn.ubuntu.com](https://usn.ubuntu.com/4458-1/) (Third-party advisory)
- [debian.org](https://www.debian.org/security/2020/dsa-4757) (Third-party advisory)

## Questions

### What is CVE-2020-9490?

CVE-2020-9490 is a high-severity flaw in HTTP Server from Apache, published on 7 August 2020. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### How serious is CVE-2020-9490?

It scores 7.5 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2020-9490 is 71 out of 100, which is High. Its action is "Patch now". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2020-9490 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 89%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2020-9490 affect?

For HTTP Server from Apache: 2.4.20 to before 2.4.46. The record lists 25 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2020-9490?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2020-9490 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

Start free (no card, nothing to install): https://www.precursorintelligence.com/register
Book a demo: https://www.precursorintelligence.com/contact