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Python: Add modelling for zstd.compression #21002

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ad68a5e
Python: Add modelling for `zstd.compression`
tausbn Dec 9, 2025
e6e0501
Python: Add change note
tausbn Dec 9, 2025
6af9fd8
Python: Make space for new test
tausbn Dec 10, 2025
d2c7147
Python: Add new test
tausbn Dec 10, 2025
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4 changes: 4 additions & 0 deletions python/ql/lib/change-notes/2025-12-09-add-modelling-of-zstd-compression.md
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@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* The `compression.zstd` library (added in Python 3.14) is now supported by the `py/decompression-bomb` query.
40 changes: 40 additions & 0 deletions python/ql/src/experimental/semmle/python/security/DecompressionBomb.qll
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Expand Up @@ -364,6 +364,46 @@ module Lzma {
}
}

/** Provides sinks and additional taint steps related to the `zstd` library in Python 3.14+. */
module Zstd {
private API::Node zstdInstance() {
result = API::moduleImport("compression").getMember("zstd").getMember(["ZstdFile", "open"])
}

/**
* The Decompression Sinks of `zstd` library
*
* `zstd.open(sink)`
* `zstd.ZstdFile(sink)`
*
* only read mode is sink
*/
class DecompressionSink extends DecompressionBomb::Sink {
DecompressionSink() {
exists(API::CallNode zstdCall | zstdCall = zstdInstance().getACall() |
this = zstdCall.getParameter(0, "filename").asSink() and
(
not exists(
zstdCall
.getParameter(1, "mode")
.getAValueReachingSink()
.asExpr()
.(StringLiteral)
.getText()
) or
zstdCall
.getParameter(1, "mode")
.getAValueReachingSink()
.asExpr()
.(StringLiteral)
.getText()
.matches("%r%")
)
)
}
}
}

/**
* `io.TextIOWrapper(ip, encoding='utf-8')` like following:
* ```python
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54 changes: 30 additions & 24 deletions python/ql/test/experimental/query-tests/Security/CWE-409/DecompressionBombs.expected
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Expand Up @@ -36,15 +36,17 @@ edges
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:45:17:45:25 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:49:15:49:23 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:50:19:50:27 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:54:40:54:48 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:56:23:56:31 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:57:21:57:29 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:54:15:54:23 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:55:19:55:27 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:59:40:59:48 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:60:22:60:30 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:61:21:61:29 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:62:42:62:50 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:63:23:63:31 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:64:36:64:44 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:61:23:61:31 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:62:21:62:29 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:64:40:64:48 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:65:22:65:30 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:66:21:66:29 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:67:42:67:50 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:68:23:68:31 | ControlFlowNode for file_path | provenance | |
| test.py:28:26:28:34 | ControlFlowNode for file_path | test.py:69:36:69:44 | ControlFlowNode for file_path | provenance | |
nodes
| test.py:10:16:10:24 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:11:5:11:35 | ControlFlowNode for Attribute() | semmle.label | ControlFlowNode for Attribute() |
Expand Down Expand Up @@ -79,15 +81,17 @@ nodes
| test.py:45:17:45:25 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:49:15:49:23 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:50:19:50:27 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:54:40:54:48 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:56:23:56:31 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:57:21:57:29 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:54:15:54:23 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:55:19:55:27 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:59:40:59:48 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:60:22:60:30 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:61:21:61:29 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:62:42:62:50 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:63:23:63:31 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:64:36:64:44 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:61:23:61:31 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:62:21:62:29 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:64:40:64:48 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:65:22:65:30 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:66:21:66:29 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:67:42:67:50 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:68:23:68:31 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
| test.py:69:36:69:44 | ControlFlowNode for file_path | semmle.label | ControlFlowNode for file_path |
subpaths
#select
| test.py:11:5:11:52 | ControlFlowNode for Attribute() | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:11:5:11:52 | ControlFlowNode for Attribute() | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
Expand All @@ -107,12 +111,14 @@ subpaths
| test.py:45:17:45:25 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:45:17:45:25 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:49:15:49:23 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:49:15:49:23 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:50:19:50:27 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:50:19:50:27 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:54:40:54:48 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:54:40:54:48 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:56:23:56:31 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:56:23:56:31 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:57:21:57:29 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:57:21:57:29 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:54:15:54:23 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:54:15:54:23 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:55:19:55:27 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:55:19:55:27 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:59:40:59:48 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:59:40:59:48 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:60:22:60:30 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:60:22:60:30 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:61:21:61:29 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:61:21:61:29 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:62:42:62:50 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:62:42:62:50 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:63:23:63:31 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:63:23:63:31 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:64:36:64:44 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:64:36:64:44 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:61:23:61:31 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:61:23:61:31 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:62:21:62:29 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:62:21:62:29 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:64:40:64:48 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:64:40:64:48 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:65:22:65:30 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:65:22:65:30 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:66:21:66:29 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:66:21:66:29 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:67:42:67:50 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:67:42:67:50 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:68:23:68:31 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:68:23:68:31 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
| test.py:69:36:69:44 | ControlFlowNode for file_path | test.py:10:16:10:24 | ControlFlowNode for file_path | test.py:69:36:69:44 | ControlFlowNode for file_path | This uncontrolled file extraction is $@. | test.py:10:16:10:24 | ControlFlowNode for file_path | depends on this user controlled data |
5 changes: 5 additions & 0 deletions python/ql/test/experimental/query-tests/Security/CWE-409/test.py
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Expand Up @@ -49,6 +49,11 @@ async def bomb(file_path):
gzip.open(file_path) # $ result=BAD
gzip.GzipFile(file_path) # $ result=BAD

from compression import zstd

zstd.open(file_path) # $ result=BAD
zstd.ZstdFile(file_path).read() # $ result=BAD

import pandas

pandas.read_csv(filepath_or_buffer=file_path) # $ result=BAD
Expand Down