CVE intelligence and bounded remediation

CVE-2020-13757 — Python-RSA before 4.1 ignores leading '\0' bytes during decryption of ciphertext

High CVSS 7.5

Python-RSA before 4.1 ignores leading '\0' bytes during decryption of ciphertext. This could conceivably have a security-relevant impact, e.g., by helping an attacker to infer that an application uses Python-RSA, or if the length of accepted ciphertext affects application behavior (such as by causing excessive memory allocation).

Severity
High
CVSS
7.5 (3.1)
Published
2020-06-01
CISA KEV
Not currently listed
Ecosystem
python/pypi
Weaknesses
CWE-327

Affected products

  • python-rsa_project / python-rsa
  • fedoraproject / fedora / 31
  • fedoraproject / fedora / 32
  • canonical / ubuntu_linux / 14.04

Matched remediation archetype

Cryptography, certificate, signature, and channel validation

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Inventory affected algorithms, key uses, trust stores, certificate validation settings, random sources, and plaintext channels across clients and services.
  • Determine which secrets, identities, signatures, or data protections depend on the affected primitive or validation path.
  • Check debug, compatibility, fallback, and hostname or audience override settings in build and runtime configuration.

Remediate safely

  • Use a maintained platform cryptographic API with approved algorithms, modes, parameters, randomness, and full peer identity validation.
  • Remove insecure fallback and validation bypasses; separate keys by purpose and load them from managed secret storage.
  • Plan rotation or reissuance for affected keys, certificates, tokens, hashes, or ciphertext and document compatibility sequencing.

Authoritative sources

Complete CVE record and remediation plan

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