How severe is CVE-2026-53956?

CVE-2026-53956 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-53956?

CVE-2026-53956 affects the following packages: rattler_cache (crates.io), py-rattler (PyPI). Ecosystems affected: crates.io, PyPI.

How do I fix CVE-2026-53956?

Update rattler_cache to 0.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53956 is resolved across your whole dependency graph.

How do I detect CVE-2026-53956 in my crates.io, PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rattler_cache. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-53956 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-53956?

O3 pinpoints whether CVE-2026-53956 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-53956 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-53956 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was CVE-2026-53956 published, and has it been updated?

CVE-2026-53956 was published on July 9, 2026 and was last updated on July 13, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀

🦀 crates.io🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2026-53956

MEDIUM

CVE-2026-53956 is a medium-severity (CVSS 5.4) vulnerability in rattler_cache. O3 Security confirms whether CVE-2026-53956 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Rattler vulnerable to package cache path traversal via conda package build string

Also known asPYSEC-2026-2970

Published

Jul 9, 2026

Updated

Jul 13, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Jul 13, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

2 pkgs affected

🦀rattler_cache🐍py-rattler

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io, PyPI packages — download data is not available via public APIs for these ecosystems.

Description

rattler_cache and py-rattler were vulnerable to package-cache path traversal when handling package metadata from conda channels.

During cache materialization, the ratter_cache code used the package record build string as part of a cache key that was joined into a filesystem path. A malicious or untrusted channel could publish repodata with path separators or traversal components in that field, causing package contents to be written outside the configured package cache directory.

The issue requires use of a malicious or otherwise untrusted conda channel. Curated channels that validate package metadata are not expected to allow malformed build strings of this form.

Users should upgrade to a patched version and avoid untrusted conda channels.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`rattler_cache`	all versions	0.9.0
🐍PyPI	`py-rattler`	all versions	0.24.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rattler_cache. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update rattler_cache to 0.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53956 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-53956 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-53956. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

`rattler_cache` and `py-rattler` were vulnerable to package-cache path traversal when handling package metadata from conda channels. During cache materialization, the `ratter_cache` code used the package record `build` string as part of a cache key that was joined into a filesystem path. A malicious or untrusted channel could publish repodata with path separators or traversal components in that field, causing package contents to be written outside the configured package cache directory. The issue requires use of a malicious or otherwise untrusted conda channel. Curated channels that validate

O3 Security · Impact-Aware SCA

Is CVE-2026-53956 in your dependencies?

O3 detects CVE-2026-53956 across crates.io, PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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