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Message-ID: <87o6k3274y.fsf@gentoo.org>
Date: Tue, 31 Mar 2026 19:20:13 +0100
From: Sam James <sam@...too.org>
To: oss-security@...ts.openwall.com
Cc: xz@...aani.org
Subject: Fwd: XZ Utils 5.8.3 and a security fix
Hi,
We've released a new xz version with some minor security fixes. It's not
believed that any application is actually vulnerable to the main one,
nor the other. It requires an unusual use of a rarely called API.
-------------------- Start of forwarded message --------------------
Date: Tue, 31 Mar 2026 19:58:29 +0300
From: Lasse Collin <lasse.collin@...aani.org>
To: xz-announce@...aani.org
Subject: XZ Utils 5.8.3 and a security fix
In XZ Utils 5.8.2 and older, a buffer overflow can occur in
lzma_index_append() under conditions that likely don't exist in any
real-world application (CVE-2026-34743). No new 5.2.x, 5.4.x, or 5.6.x
releases will be made, but the fix is in the v5.2, v5.4, and v5.6
branches in the xz Git repository. For details, see the NEWS entry
below or the security advisory:
https://tukaani.org/xz/index-append-overflow.html
XZ Utils 5.8.3 is available at <https://tukaani.org/xz/#_stable>.
5.8.3 (2026-03-31)
* liblzma:
- Fix a buffer overflow in lzma_index_append(): If
lzma_index_decoder() was used to decode an Index that
contained no Records, the resulting lzma_index was left in
a state where where a subsequent lzma_index_append() would
allocate too little memory, and a buffer overflow would occur.
The lzma_index functions are rarely used by applications
directly. In the few applications that do use these functions,
the combination of function calls required to trigger this bug
are unlikely to exist, because there typically is no reason to
append Records to a decoded lzma_index. Thus, it's likely that
this bug cannot be triggered in any real-world application.
The bug was reported and discovered by Cantina using their
AppSec agent, Apex.
- Fix the build on Windows ARM64EC.
- Add "License: 0BSD" to liblzma.pc.
* xz:
- Fix invalid memory access in --files and --files0. All of
the following must be true to trigger it:
1. A string being read (which supposedly is a filename) is
at least SIZE_MAX / 2 bytes long. This size is plausible
on 32-bit platforms (2 GiB - 1 B).
2. realloc(ptr, SIZE_MAX / 2 + 1) must succeed.
On glibc >= 2.30 it shouldn't because the value
exceeds PTRDIFF_MAX.
3. An integer overflow results in a realloc(ptr, 0) call.
If it doesn't return NULL, then invalid memory access
will occur.
- On QNX, don't use fsync() on directories because it fails.
* Autotools: Enable 32-bit x86 assembler on Hurd by default.
It was already enabled in the CMake-based build.
* Translations: Add Arabic man page translations.
--
Lasse Collin
-------------------- End of forwarded message --------------------
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