Cryptography vulnerable to buffer overflow if non-contiguous buffers were passed to APIs

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-39892: 0.65% estimated exploitation activity in the next 30 days; percentile 51.30 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

If a non-contiguous buffer was passed to APIs which accepted Python buffers (e.g. `Hash.update()`), this could lead to buffer overflows. For example: ```python h = Hash(SHA256()) b.update(buf[::-1]) ``` would read past the end of the buffer on Python >3.11

Published by the source

8 Apr 2026, 19:23 UTC

Last modified by the source

4 Nov 2026, 03:30 UTC

Source last checked

4 Nov 2026, 06:20 UTC

1. Revision 5 · amended · 4 Nov 2026

   Amended from osv record GHSA-p423-j2cm-9vmq

2. Revision 4 · amended · 4 Nov 2026

   Amended from ghsa record GHSA-p423-j2cm-9vmq

3. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-p423-j2cm-9vmq

4. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

5. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-p423-j2cm-9vmq

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# Patch Next advisory brief: CVE-2026-39892

Advisory: Cryptography vulnerable to buffer overflow if non-contiguous buffers were passed to APIs
IDs: CVE-2026-39892, GHSA-p423-j2cm-9vmq
Record: https://patchnext.com/advisories/cve-2026-39892 (revision 5, source checked 4 Nov 2026, 06:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: cryptography 46.0.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI cryptography: affected >= 45.0.0, < 46.0.7; fixed in 46.0.7

## Suggested inspection (read-only)
- `python -m pip show cryptography`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on cryptography.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-p423-j2cm-9vmq (OSV record GHSA-p423-j2cm-9vmq lists affected ranges: PyPI cryptography >=45.0.0 <46.0.7 (fixed))
- Verified: https://github.com/advisories/GHSA-p423-j2cm-9vmq (GitHub-reviewed advisory GHSA-p423-j2cm-9vmq lists affected ranges: PyPI cryptography >=45.0.0 <46.0.7)

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