Bug 2540878 - CVE-2026-28386 openssl: openssl: Denial of Service due to out-of-bounds read in AES-CFB128 [fedora-all]
Summary: CVE-2026-28386 openssl: openssl: Denial of Service due to out-of-bounds read ...
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Fedora
Classification: Fedora
Component: openssl
Version: rawhide
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: ---
Assignee: Dmitry Belyavskiy
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["3991d7db-1e70-4903-9583-3...
Depends On:
Blocks: CVE-2026-28386
TreeView+ depends on / blocked
 
Reported: 2026-09-25 00:42 UTC by Patrick Del Bello
Modified: 2026-09-25 11:45 UTC (History)
8 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2026-09-25 11:45:06 UTC
Type: ---
Embargoed:
fedora-admin-xmlrpc: mirror+


Attachments (Terms of Use)

Description Patrick Del Bello 2026-09-25 00:42:04 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.

Issue summary: Applications using AES-CFB128 encryption or decryption on
systems with AVX-512 and VAES support can trigger an out-of-bounds read
of up to 15 bytes when processing partial cipher blocks.

Impact summary: This out-of-bounds read may trigger a crash which leads to
Denial of Service for an application if the input buffer ends at a memory
page boundary and the following page is unmapped. There is no information
disclosure as the over-read bytes are not written to output.

The vulnerable code path is only reached when processing partial blocks
(when a previous call left an incomplete block and the current call provides
fewer bytes than needed to complete it). Additionally, the input buffer
must be positioned at a page boundary with the following page unmapped.
CFB mode is not used in TLS/DTLS protocols, which use CBC, GCM, CCM, or
ChaCha20-Poly1305 instead.

Comment 1 Dmitry Belyavskiy 2026-09-25 11:45:06 UTC
Relevant for openssl 3.6.0-3.6.2, we don't ship any version of this range


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