CVE-2023-23931

Cipher.update_into can corrupt memory in pyca cryptography

MEDIUM
6.5
CVSS Score
Published: February 7, 2023 at 08:54 PM UTC
Updated: June 17, 2026 at 05:38 AM UTC
2 products affected across 2 vendorsCryptographyCryptography

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Severity
MEDIUM6.5
Exploit prediction
EPSS 1%
SSVC
PoC

Description

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In affected versions `Cipher.update_into` would accept Python objects which implement the buffer protocol, but provide only immutable buffers. This would allow immutable objects (such as `bytes`) to be mutated, thus violating fundamental rules of Python and resulting in corrupted output. This now correctly raises an exception. This issue has been present since `update_into` was originally introduced in cryptography 1.8.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

1.8 ≤ v < 39.0.1
Affected range stops below 39.0.1, so it looks safe — our inference, not a vendor statement
v < 39.0.1
Affected range stops below 39.0.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
LOW
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-754

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