RHSA-2026:7295
Vulnerability from csaf_redhat - Published: 2026-04-09 11:17 - Updated: 2026-04-24 12:38A validation flaw has been discovered in the python cryptography package. This missing validation allows an attacker to provide a public key point P from a small-order subgroup. This can lead to security issues in various situations, such as the most commonly used signature verification (ECDSA) and shared key negotiation (ECDH). When the victim computes the shared secret as S = [victim_private_key]P via ECDH, this leaks information about victim_private_key mod (small_subgroup_order). For curves with cofactor > 1, this reveals the least significant bits of the private key. When these weak public keys are used in ECDSA , it's easy to forge signatures on the small subgroup. Only SECT curves are impacted by this.
A flaw was found in the `cryptography` library. This vulnerability occurs because DNS (Domain Name System) name constraints were not properly validated against the "peer name" during certificate validation, only against Subject Alternative Names (SANs) within child certificates. This oversight could allow a malicious actor to bypass security restrictions, enabling a certificate for a specific domain to be validated against a broader wildcard certificate, even when an exclusion for that specific domain exists. This could lead to an attacker impersonating a legitimate server or service.
CWE-295 - Improper Certificate ValidationA flaw was found in the cryptography library. This vulnerability occurs when a non-contiguous buffer is passed to certain application programming interfaces (APIs) that accept Python buffers, such as Hash.update(). A remote attacker could exploit this to cause a buffer overflow, potentially leading to a denial of service.
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.