Cyber Resilience

CVE-2026-39892

Memory Safety in Cryptography.Io Cryptography 45.0.0 – 46.0.7

Memory Safety
Published
08 April 2026
Modified
12 August 2026
Patch / advisory
View advisory
CVSS Score v4 6.9
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0065 48th percentile
Risk Priority 42 floored blend · peak EPSS

Summary

CVE-2026-39892 is a medium-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Cryptography.Io Cryptography. Its CVSS base score is 6.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 48th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-39892 is a buffer overflow vulnerability (CWE-119) in the cryptography Python package, which exposes cryptographic primitives and recipes to Python developers. The flaw affects versions from 45.0.0 up to but not including 46.0.7, where passing a non-contiguous buffer to APIs accepting Python buffers, such as Hash.update(), can trigger buffer overflows.

The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating it is exploitable remotely over the network by any unauthenticated attacker with low attack complexity and no user interaction. Exploitation could lead to high impacts on confidentiality, integrity, and availability, such as arbitrary code execution or system crashes via the buffer overflow.

The issue is addressed in cryptography version 46.0.7. Additional mitigation details are available in the GitHub security advisory at https://github.com/pyca/cryptography/security/advisories/GHSA-p423-j2cm-9vmq and the oss-security mailing list post at http://www.openwall.com/lists/oss-security/2026/04/08/12.

EU & UK References

Vulnerability Data

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. From 45.0.0 to before 46.0.7, if a non-contiguous buffer was passed to APIs which accepted Python buffers (e.g. Hash.update()), this could lead to buffer overflows. This…

more

vulnerability is fixed in 46.0.7.

CWE(s)
CWE-119CWE-131

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1055 Process Injection Stealth
Adversaries may inject code into processes in order to evade process-based defenses as well as possibly elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-23931Same product: Cryptography.Io Cryptography
CVE-2024-26130Same product: Cryptography.Io Cryptography
CVE-2026-26007Same product: Cryptography.Io Cryptography
CVE-2026-34073Same product: Cryptography.Io Cryptography
CVE-2023-49083Same product: Cryptography.Io Cryptography
CVE-2023-38325Same product: Cryptography.Io Cryptography
CVE-2026-10701Shared CWE-119, CWE-131
CVE-2026-6752Shared CWE-119, CWE-131
CVE-2026-16393Shared CWE-119
CVE-2016-7193Shared CWE-119

Affected Assets

cryptography.io
cryptography
45.0.0 — 46.0.7

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V17.3.2

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer security testing and code review can discover incorrect buffer-size computations before deployment.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require memory-safe design and coding that structurally avoids buffer-boundary violations.

SI-10 Information Input Validation partial match

Input validation directly enforces bounds checking that stops out-of-bounds reads/writes from being introduced or reached.

SI-16 Memory Protection partial match

Memory protection restricts exploitation impact of buffer overflows without eliminating the underlying coding flaw.

SI-2 Flaw Remediation partial match

Flaw-remediation processes that include vulnerability scanning or static analysis will surface buffer-size errors.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices (bounds checking, safe APIs, reviews) directly prevent this class of flaw.

ID.RA-01 partial match
prevents

Vulnerability scanning and code analysis directly surface buffer-boundary flaws.

ID.RA-08 partial match
prevents

Receiving and triaging vulnerability disclosures commonly includes buffer-related reports.

PR.AT-02 partial match
prevents

Developer training on secure coding reduces introduction of memory-buffer errors.

PR.PS-02 partial match
prevents

Patching replaces vulnerable code containing buffer-boundary defects.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding mostly match
degrades

Secure coding standards directly require correct buffer-size calculations.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches out-of-bounds accesses before release, covering most instances of the weakness.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates memory-safety practices that directly prevent buffer-boundary violations.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify memory-safety rules, but do not prescribe implementation details.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture and engineering principles include memory-safe design patterns that mitigate buffer overflows.

References