Bug 2554197

Summary: CVE-2026-77214 mingw-expat: expat: Information disclosure via heap buffer over-read in XML_ParseBuffer [fedora-all]
Product: [Fedora] Fedora Reporter: Florencio Cano <fcanogab>
Component: mingw-expatAssignee: Richard Jones <rich>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: manisandro, rjones
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["80149298-bc03-4404-9a11-7cc719e64c13"]}
Fixed In Version: mingw-expat-2.9.0-1.fc45 mingw-expat-2.9.0-1.fc44 Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-11-01 01:04:28 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2547476    

Description Florencio Cano 2026-10-16 16:33:34 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER. A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap memory to the calling application, recovering heap pointers, libc function pointers, and code pointers sufficient to defeat ASLR and build further exploitation primitives.
Comment 1 Fedora Update System 2026-10-23 09:40:18 UTC 
FEDORA-2026-86ef30a678 (mingw-expat-2.9.0-1.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-86ef30a678
Comment 2 Fedora Update System 2026-10-23 09:40:22 UTC 
FEDORA-2026-3c5a339682 (mingw-expat-2.9.0-1.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-3c5a339682
Comment 3 Fedora Update System 2026-10-24 17:25:35 UTC 
FEDORA-2026-86ef30a678 has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-86ef30a678`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-86ef30a678

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 4 Fedora Update System 2026-10-24 18:15:29 UTC 
FEDORA-2026-3c5a339682 has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-3c5a339682`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-3c5a339682

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 5 Fedora Admin user for bugzilla script actions 2026-10-29 14:01:15 UTC 
This package has changed maintainer in Fedora. Reassigning to the new maintainer of this component.
Comment 6 Fedora Update System 2026-11-01 01:04:28 UTC 
FEDORA-2026-3c5a339682 (mingw-expat-2.9.0-1.fc45) has been pushed to the Fedora 45 stable repository.
If problem still persists, please make note of it in this bug report.
Comment 7 Fedora Update System 2026-11-01 03:34:33 UTC 
FEDORA-2026-3c5a339682 (mingw-expat-2.9.0-1.fc45) has been pushed to the Fedora 45 stable repository.
If problem still persists, please make note of it in this bug report.
Comment 8 Fedora Update System 2026-11-01 03:35:06 UTC 
FEDORA-2026-86ef30a678 (mingw-expat-2.9.0-1.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.