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TI-2026-02971 Aliases CVE-2026-3446GHSA-8r9f-h969-mm4m

Base64 decoding stops at first padded quad by default

Priority LOW 26CWE-345Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
High
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
None · High · None
Fix status
Partial Red Hat: 1 fixed, 2 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-345.

Summary

When calling base64.b64decode() or related functions the decoding process would stop after encountering the first padded quad regardless of whether there was more information to be processed. This can lead to data being accepted which may be processed differently by other implementations. Use "validate=True" to enable stricter processing of base64 data.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00179 7th percentileScored 2026-11-07
Fix Partial CPython (Python Software Foundation): 3.13.13, 3.14.4, 3.15.0a8Red Hat: 5 advisoriesRed Hat: 1 fixed, 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Python Software FoundationCPythonbefore 3.13.13; 3.14.0 to before 3.14.4; 3.15.0a1 to before 3.15.0a83.13.13, 3.14.4, 3.15.0a8Patch availableCNA
  • CPython VendorPython Software Foundation Affected before 3.13.13; 3.14.0 to before 3.14.4; 3.15.0a1 to before 3.15.0a8 Fixed in 3.13.13, 3.14.4, 3.15.0a8 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*——python-pillow
  • cpe:2.3:a:python:python:*:*:*:*:*:*:*:* Versions — — ·python-pillow

Remediation

  • Fix · CNA CPython (Python Software Foundation) Fixed in 3.13.13, 3.14.4, 3.15.0a8

Red Hat 5 advisories

  • RHSA-2026:60511 Released 2026-08-27 · Red Hat rating Moderate
    Red Hat Hardened Images RPMs Security Update
    • Red Hat Hardened Images python3.11-3.11.16-1.1.hum1@aarch64, python3.11-3.11.16-1.1.hum1@src, python3.11-3.11.16-1.1.hum1@x86_64 +12
  • RHSA-2026:58420 Released 2026-08-21 · Red Hat rating Moderate
    Red Hat Hardened Images RPMs Security Update
    • Red Hat Hardened Images python3.12-3.12.14-1.hum1@aarch64, python3.12-3.12.14-1.hum1@src, python3.12-3.12.14-1.hum1@x86_64 +12
  • RHSA-2026:10118 Released 2026-04-23 · Red Hat rating Moderate
    Red Hat Hardened Images RPMs Security Update
    • Red Hat Hardened Images python3.12-3.12.13-3.1.hum1@aarch64, python3.12-3.12.13-3.1.hum1@src, python3.12-3.12.13-3.1.hum1@x86_64 +12
Show 2 more Red Hat advisories
  • RHSA-2026:7661 Released 2026-04-11 · Red Hat rating Important
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images python-unversioned-command-3.14.4-1.hum1@noarch@public-hummingbird-aarch64-rpms, python-unversioned-command-3.14.4-1.hum1@noarch@public-hummingbird-x86_64-rpms, python3-3.14.4-1.hum1@aarch64 +28
  • RHSA-2026:7443 Released 2026-04-10 · Red Hat rating Important
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images python3.13-3.13.13-1.hum1@aarch64, python3.13-3.13.13-1.hum1@src, python3.13-3.13.13-1.hum1@x86_64 +16

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred
Red Hat Hardened ImagesFixed RHSA-2026:10118, RHSA-2026:58420, RHSA-2026:60511, RHSA-2026:7443, RHSA-2026:7661
Not affected: 5 products
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-3446
  2. 2026-10-03 Alias added: GHSA-8r9f-h969-mm4m
  3. 2026-11-06 Affected versions changed · Red Hat

References

Patch 4

Advisory 1

Other 1

  • TI-2024-07037 Quadratic complexity parsing cookies with backslashes CVSS 3.1HIGH 7.5
  • TI-2024-11791 Bypass extraction filter to modify file metadata outside extraction directory CVSS 3.1MEDIUM 5.3
  • TI-2024-00411 Quoted zip-bomb protection for zipfile CVSS 3.1MEDIUM 6.2
  • TI-2026-13296 `HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching CVSS 4.0MEDIUM 6.0
  • TI-2024-06422 Email header injection due to unquoted newlines CVSS 3.1MEDIUM 5.5
  • TI-2026-04606 Possible to hijack modules in current working directory CVSS 4.0MEDIUM 5.6
See all 83 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences