Bug 2500960 (CVE-2026-56434)

Summary: CVE-2026-56434 nginx: NGINX: Heap buffer over-read allows memory modification or denial of service
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: gsciorti, kaycoth, rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A vulnerability in NGINX's ngx_http_ssi_module allows an unauthenticated MITM attacker to trigger a heap buffer over-read by manipulating upstream server responses. This requires SSI, proxy_pass, and proxy_buffering off to be configured, and can result in memory modification or a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2508273    
Bug Blocks:    

Description OSIDB Bzimport 2026-07-15 15:01:34 UTC 
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a heap buffer over-read in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process.

Impact:
This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Comment 3 errata-xmlrpc 2026-08-24 23:10:34 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:59220 https://access.redhat.com/errata/RHSA-2026:59220
Comment 4 errata-xmlrpc 2026-08-24 23:13:57 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:59216 https://access.redhat.com/errata/RHSA-2026:59216
Comment 5 errata-xmlrpc 2026-08-25 14:06:59 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:59362 https://access.redhat.com/errata/RHSA-2026:59362
Comment 6 errata-xmlrpc 2026-08-25 17:29:17 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:59490 https://access.redhat.com/errata/RHSA-2026:59490
Comment 7 errata-xmlrpc 2026-08-25 18:43:38 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:59496 https://access.redhat.com/errata/RHSA-2026:59496