Security readout for executives and security teams
Plain-English summary
Apache HTTP Server 2.4.26 can mishandle HTTP/2 connections under stress and access memory after it was freed. The documented impact is potentially erratic behavior, not a confirmed takeover scenario. Public-facing web servers using this exact version and HTTP/2 deserve attention, but the supplied sources do not provide a severity score.
Executive priority
Treat this as a targeted web-server hygiene item, not an emergency based on the supplied evidence. Prioritize confirmation and vendor-supported updates for externally exposed Apache 2.4.26 systems using HTTP/2.
Technical view
CVE-2017-9789 is a read-after-free issue in Apache httpd 2.4.26 mod_http2. It can occur when many connections are being closed under stress. The source bundle identifies Apache HTTP Server 2.4.26 as affected and describes the result as potentially erratic behavior. No CVSS vector or CWE is provided.
Likely exposure
Exposure appears limited to Apache HTTP Server 2.4.26 deployments using HTTP/2 handling. Internet-facing servers, reverse proxies, and appliances bundling Apache httpd should be checked, especially where vendor advisories from Apple, HPE, NetApp, or Gentoo apply.
Exploitation context
The provided data does not show CISA KEV listing or other evidence of active exploitation. The issue is stress-related and connection-handling dependent. Treat exploitability details as incomplete from the supplied sources.
Researcher notes
Evidence is sparse: no CVSS, CWE, exploit status, or detailed fix data is present in the bundle. Analysis should stay tied to Apache httpd 2.4.26 mod_http2 and the described read-after-free during stressed connection closure.
Mitigation direction
- Identify Apache HTTP Server 2.4.26 systems with HTTP/2 enabled.
- Review Apache and operating-system vendor advisories for fixed packages.
- Upgrade through supported vendor channels where an advisory provides an update.
- If patching is delayed, assess vendor-supported HTTP/2 mitigation options.
- Prioritize public-facing and high-traffic web tiers first.
Validation and detection
- Confirm installed Apache httpd version on each web server or appliance.
- Check whether mod_http2 or HTTP/2 support is enabled.
- Review vendor package advisories for the deployed platform.
- Look for crash reports or instability during high connection churn.
- Document systems that are not running Apache HTTP Server 2.4.26.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2017-9789 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- [announce] 20170713 CVE-2017-9789: Apache httpd 2.4 Read after free in mod_http2CVE reference · mailing-list, x_refsource_MLIST
- https://support.apple.com/HT208221CVE reference · x_refsource_CONFIRM
- https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03908en_usCVE reference · x_refsource_CONFIRM
- https://security.netapp.com/advisory/ntap-20170911-0002/CVE reference · x_refsource_CONFIRM
- https://httpd.apache.org/security/vulnerabilities_24.htmlCVE reference · x_refsource_CONFIRM
- GLSA-201710-32CVE reference · vendor-advisory, x_refsource_GENTOO
- [httpd-cvs] 20190815 svn commit: r1048743 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlCVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20190815 svn commit: r1048742 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlCVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20200401 svn commit: r1058586 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlCVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20200401 svn commit: r1058587 [4/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlCVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210330 svn commit: r1073139 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE reference · mailing-list, x_refsource_MLIST
- [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.htmlCVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210330 svn commit: r1073139 [11/13] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210330 svn commit: r1888194 [11/13] - /httpd/site/trunk/content/security/json/CVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210330 svn commit: r1073149 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/CVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210330 svn commit: r1073149 [11/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/CVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210330 svn commit: r1073146 [3/3] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities-httpd.xml security/vulnerabilities_22.html security/vulnerabilities_24.htmlCVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210603 svn commit: r1075360 [3/3] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlCVE reference · mailing-list, x_refsource_MLIST
- [httpd-cvs] 20210606 svn commit: r1075467 [2/2] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.htmlCVE reference · mailing-list, x_refsource_MLIST
- [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.htmlCVE reference · mailing-list, x_refsource_MLIST
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.