How severe is GHSA-g6cj-pr64-35w5?

No CVSS score has been assigned to GHSA-g6cj-pr64-35w5 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-g6cj-pr64-35w5?

GHSA-g6cj-pr64-35w5 affects the following packages: cryptography (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-g6cj-pr64-35w5?

Update cryptography to 50.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g6cj-pr64-35w5 is resolved across your whole dependency graph.

How do I detect GHSA-g6cj-pr64-35w5 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cryptography, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-g6cj-pr64-35w5 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 GHSA-g6cj-pr64-35w5?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-g6cj-pr64-35w5 can be triaged on real exposure rather than presence alone.

Is GHSA-g6cj-pr64-35w5 actively exploited in the wild?

No public exploit code has been indexed for GHSA-g6cj-pr64-35w5 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.

What is the EPSS score for GHSA-g6cj-pr64-35w5?

GHSA-g6cj-pr64-35w5 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 7th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-g6cj-pr64-35w5?

GHSA-g6cj-pr64-35w5 is classified as CWE-208 (CWE-208), CWE-209 (CWE-209). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-g6cj-pr64-35w5 published, and has it been updated?

GHSA-g6cj-pr64-35w5 was published on August 3, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

GHSA-g6cj-pr64-35w5 — cryptography

Fix: pyca/cryptography#15369

GHSA-g6cj-pr64-35w5 is a CWE-208 vulnerability in cryptography. A fix is available for cryptography — see the affected versions and patch details below.

cryptography: PKCS#7 EnvelopedData decryption exposes a Bleichenbacher oracle through distinguishable errors and timing

Also known asCVE-2026-69247PYSEC-2026-3552

Published

Aug 3, 2026

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 18, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-g6cj-pr64-35w5.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs7th percentile — riskier than 7% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected

🐍cryptography

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

Description

Summary

pkcs7_decrypt_der, pkcs7_decrypt_pem, and pkcs7_decrypt_smime reported the outcome of decrypting a RecipientInfo's encryptedKey in several distinguishable ways, one of which disclosed the exact length recovered from the RSA operation. The same distinction was also observable by timing. An application that decrypts attacker-supplied EnvelopedData and reflects the outcome gives the attacker a Bleichenbacher oracle against the content-encryption key.

Introduced in 44.0.0. Fixed in 50.0.0.

Details

Decryption ran as: RSA PKCS#1 v1.5 decrypt of encryptedKey → build an AES cipher from the result → AES-CBC decrypt and PKCS#7 unpad. Each stage failed differently, with no RFC 3218 mitigation:

invalid RSA padding → Decryption failed
valid padding, bad key length → Invalid key size (N) for AES., disclosing N
correct length, wrong key → Invalid padding bytes.
the real key → plaintext

Case 1 is reachable only where the linked library lacks implicit rejection: OpenSSL 3.0 and 3.1, LibreSSL, and BoringSSL. On OpenSSL 3.2+, used in our wheels, invalid padding instead returns a synthetic plaintext of pseudorandom length, so the error channel does not distinguish conforming ciphertexts.

Exploitation requires a service that auto-decrypts untrusted EnvelopedData matching the victim certificate and answers adaptively at high volume, such as an S/MIME gateway or mail filter.

Fix

Per RFC 3218, the content-encryption algorithm is now resolved before the private key is used, so the expected key length is known in advance. If the RSA decryption fails or recovers a key of the wrong length, a random key of the expected length is substituted and decryption continues down an identical path. All failures now report identically and perform the same work.

Not addressed by this fix

EnvelopedData does not authenticate its content. Tampering with encryptedContent alone yields a CBC padding oracle that recovers plaintext at roughly 256 queries per byte, without recovering any key, on every backend. This is a property of PKCS#7 rather than of this implementation, cannot be fixed in the library, and is now documented.

Credit

Reported by @X1AOxiang.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`cryptography`	≥ 44.0.0&&< 50.0.0	50.0.0`pip install --upgrade 'cryptography==50.0.0'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cryptography, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update cryptography to 50.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g6cj-pr64-35w5 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-g6cj-pr64-35w5 can be triaged on real exposure rather than presence alone.

Tailored to GHSA-g6cj-pr64-35w5. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Red Hat rates this Moderate (CVSS 3.1 5.9). Exploitation requires an application that decrypts attacker-supplied PKCS#7 EnvelopedData via pkcs7_decrypt_* and leaks errors or timing. GitHub CNA CVSS 4.0 8.2 assumes that oracle is readily available.

Product	Fixed in	Advisory
Red Hat Hardened Images	`python-cryptography-main-50.0.0-1.hum1`	RHSA-2026:55543

Ubuntu

USN-8776-1Ubuntu

Frequently Asked Questions

### Summary `pkcs7_decrypt_der`, `pkcs7_decrypt_pem`, and `pkcs7_decrypt_smime` reported the outcome of decrypting a `RecipientInfo`'s `encryptedKey` in several distinguishable ways, one of which disclosed the exact length recovered from the RSA operation. The same distinction was also observable by timing. An application that decrypts attacker-supplied `EnvelopedData` and reflects the outcome gives the attacker a Bleichenbacher oracle against the content-encryption key. Introduced in 44.0.0. Fixed in 50.0.0. ### Details Decryption ran as: RSA PKCS#1 v1.5 decrypt of `encryptedKey` → build

O3 Security · Impact-Aware SCA

Is GHSA-g6cj-pr64-35w5 in your dependencies?

O3 Security finds GHSA-g6cj-pr64-35w5 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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