CVE-2020-35917 json
Reference counting error in pyo3
published 2020-11-28 5 y ago modified 2026-06-17 4 mo ago also GHSA-2vx6-fcw6-hpr6 , RUSTSEC-2020-0074 , EUVD-2021-1519
- cvss
- 5.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 33%
- public exploits
- 0
- none known
Summary
An issue was discovered in the pyo3 crate before 0.12.4 for Rust. There is a reference-counting error and use-after-free in From<Py<T>>.
Patch / fix
- crates.io pyo3 0.12.4
- pyo3_project pyo3 0.12.4
- github.com/PyO3/pyo3@8f81f59 commit
- github.com/PyO3/pyo3#1297 pull request
- rustsec.org/advisories/RUSTSEC-2020-0074.html advisory
Exploit prediction
0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- rustsec.org https://rustsec.org/advisories/RUSTSEC-2020-0074.html referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| NVD | 2.0 | 2.1 | AV:L/AC:L/Au:N/C:N/I:N/A:P |
| OSV | 3.1 | 5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| GitHub | 3.1 | 5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| crates.io | pyo3 | >=0.12.0, <0.12.4 |
0.12.4 |
Classification
- Weakness
-
- CWE-416 Use After Free
References
-
rustsec.org
/advisories/RUSTSEC-2020-0074.html
web, exploit, patch, third-party-advisory, advisory
-
github.com
/PyO3/pyo3/pull/1297
web
-
github.com
/PyO3/pyo3/commit/8f81f595dd770b586c7ca7195b42004a6c976eb9
web
-
nvd.nist.gov
/vuln/detail/CVE-2020-35917
advisory
-
github.com
/PyO3/pyo3
package
-
crates.io
/crates/pyo3
package
Sources
- CVE List CVE-2020-35917
- GitHub Advisory GHSA-2vx6-fcw6-hpr6
- NVD CVE-2020-35917
- OSV RUSTSEC-2020-0074
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.