https://github.com/python/cpython/commit/47128e64f98c3a20271138a98c2922bea2a3ee0e
commit: 47128e64f98c3a20271138a98c2922bea2a3ee0e
branch: 3.10
author: Stan Ulbrych <[email protected]>
committer: pablogsal <[email protected]>
date: 2026-04-13T22:42:24+01:00
summary:
[3.10] gh-148395: Fix a possible UAF in `{LZMA,BZ2}Decompressor` (GH-148396)
(#148505)
Fix dangling input pointer after `MemoryError` in
_lzma/_bz2/_ZlibDecompressor.decompress
(cherry picked from commit 8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2)
files:
A Misc/NEWS.d/next/Security/2026-04-10-16-28-21.gh-issue-148395.kfzm0G.rst
M Modules/_bz2module.c
M Modules/_lzmamodule.c
diff --git
a/Misc/NEWS.d/next/Security/2026-04-10-16-28-21.gh-issue-148395.kfzm0G.rst
b/Misc/NEWS.d/next/Security/2026-04-10-16-28-21.gh-issue-148395.kfzm0G.rst
new file mode 100644
index 00000000000000..b095329bd913b0
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2026-04-10-16-28-21.gh-issue-148395.kfzm0G.rst
@@ -0,0 +1,5 @@
+Fix a dangling input pointer in :class:`lzma.LZMADecompressor`,
+:class:`bz2.BZ2Decompressor`
+when memory allocation fails with :exc:`MemoryError`, which could let a
+subsequent :meth:`!decompress` call read or write through a stale pointer to
+the already-released caller buffer.
diff --git a/Modules/_bz2module.c b/Modules/_bz2module.c
index 798e9efc628f05..b08ac5e44e52f4 100644
--- a/Modules/_bz2module.c
+++ b/Modules/_bz2module.c
@@ -595,6 +595,7 @@ decompress(BZ2Decompressor *d, char *data, size_t len,
Py_ssize_t max_length)
return result;
error:
+ bzs->next_in = NULL;
Py_XDECREF(result);
return NULL;
}
diff --git a/Modules/_lzmamodule.c b/Modules/_lzmamodule.c
index 915c0c918f6443..52087c38cb225e 100644
--- a/Modules/_lzmamodule.c
+++ b/Modules/_lzmamodule.c
@@ -1102,6 +1102,7 @@ decompress(Decompressor *d, uint8_t *data, size_t len,
Py_ssize_t max_length)
return result;
error:
+ lzs->next_in = NULL;
Py_XDECREF(result);
return NULL;
}
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