Summary
Package updates are available for Amazon Linux 2023 that fix the following vulnerabilities: CVE-2026-6100: Use-after-free (UAF) was possible in the `lzma.LZMADecompressor`, `bz2.BZ2Decompressor`, and `gzip.GzipFile` when a memory allocation fails with a `MemoryError` and the decompression instance is re-used. This scenario can be triggered if the process is under memory pressure. The fix cleans up the dangling pointer in this specific error condition. The vulnerability is only present if the program re-uses decompressor instances across multiple decompression calls even after a `MemoryError` is raised during decompression. Using the helper functions to one-shot decompress data such as `lzma.decompress()`, `bz2.decompress()`, `gzip.decompress()`, and `zlib.decompress()` are not affected as a new decompressor instance is used per call. If the decompressor instance is not re-used after an error condition, this usage is similarly not vulnerable. CVE-2026-4786: Mitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details. CVE-2026-4224: When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs. CVE-2026-3644: The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().
Fixed packages 9
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2023 | python3.12 | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-debug | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-debuginfo | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-debugsource | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-devel | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-idle | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-libs | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-test | 0:3.12.13-2.amzn2023.0.1 |
| Amazon Linux · 2023 | python3.12-tkinter | 0:3.12.13-2.amzn2023.0.1 |
Vulnerabilities 4
-
Critical 9.1
Use-after-free in lzma.LZMADecompressor, bz2.BZ2Decompressor, and gzip.GzipFile after re-use under memory pressure
Use-after-free (UAF) was possible in the `lzma.LZMADecompressor`, `bz2.BZ2Decompressor`, and `gzip.GzipFile` when a memory allocation fails with a `MemoryError` and the decompression instance is re-used. This scenario can be triggered if the process is under …
-
High 7.0
Incomplete mitigation of CVE-2026-4519, %action expansion for command injection to webbrowser.open()
Mitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details.
-
Medium 6.0
Incomplete control character validation in http.cookies
The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_o…
-
Medium 6.0
Stack overflow parsing XML with deeply nested DTD content models
When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.