GHSA-pph8-gcv7-4qj5 RUSTSEC-2025-0020
PyO3 Risk of buffer overflow in `PyString::from_object`
- Severity
- 0.0 / 10
- Low · CVSS 4.0
- Exploit chance (EPSS)
- —
- No score published
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-125 Out-of-bounds Read
- Fix
0.24.1- Upgrade pyo3 to this version or later
Description
PyString::from_object took &str arguments and forwarded them directly to the Python C API without checking for terminating nul bytes. This could lead the Python interpreter to read beyond the end of the &str data and potentially leak contents of the out-of-bounds read (by raising a Python exception containing a copy of the data including the overflow).
In PyO3 0.24.1 this function will now allocate a CString to guarantee a terminating nul bytes. PyO3 0.25 will likely offer an alternative API which takes &CStr arguments.
Affected versions
crates.io
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
pyo3 crates.io → 0.24.1
- cargo
cargo update -p pyo3 --precise 0.24.1
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- Present
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- Low
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Proof of concept
Weakness
CWE-125: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How to prevent it
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.
- Architecture and Design: Use a language that provides appropriate memory abstractions.
References
Packages
Other links
Timeline
- Published
- Last updated by the source
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-chgr-c6px-7xpp PyO3 has a missing `Sync` bound on `PyCFunction::new_closure` closures | Medium | Also affects pyo3 |
| GHSA-36hh-v3qg-5jq4 PyO3 has an Out-of-bounds Read in `nth` / `nth_back` for `PyList` and `PyTuple` iterators | High | Also affects pyo3 |
| GHSA-47qc-857f-7w7f PyO3 has type confusion when accessing data from sublasses of subclasses of native types with `abi3` feature | High | Also affects pyo3 |
| GHSA-vxcf-c7mx-pg53 Build corruption when using `PYO3_CONFIG_FILE` environment variable | Medium | Also affects pyo3 |
| GHSA-6jgw-rgmm-7cv6 PyO3 has a risk of use-after-free in `borrowed` reads from Python weak references | Medium | Also affects pyo3 |
| GHSA-2vx6-fcw6-hpr6 Reference counting error in pyo3 | Medium | Also affects pyo3 |
| GHSA-9v9v-9qvf-h2hj Pillow: Heap over-read in WMF/EMF rendering via 16-bit dimension truncation (Windows builds) | High | Same weakness, CWE-125 |
| GHSA-v9pv-5gc8-w2m6 Pillow multi-frame loaders can reuse stale native image storage after mode transitions | Critical | Same weakness, CWE-125 |
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