CVE-2026-3644

Incomplete control character validation in http.cookies

At a glance

Severity: MEDIUM 6.0
EPSS: EPSS 0.50 % · percentile 42 (2026-10-27)
State: PUBLISHED
Published: 2026-03-16
Updated: 2026-08-13
Assigner: PSF
NVD status: Modified

Description

The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().

Scores

Version	Score	Vector	Scored by
CVSS 4.0	MEDIUM 6.0	CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N	PSF
CVSS 4.0	MEDIUM 6.0	CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/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	NVD · cna@python.org (Secondary)
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N	NVD · nvd@nist.gov (Primary)

Weaknesses (CWE)

European references

ENISA EUVD · EUVD-2026-12484
GCVE · GCVE-0-2026-3644

CERT-FR advisories

CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
CERTFR-2026-AVI-0556 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
CERTFR-2026-AVI-0302 — Multiples vulnérabilités dans Python · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

cpe:2.3:a:python:python:*:*:*:*:*:*:*:* < 3.13.13
cpe:2.3:a:python:python:*:*:*:*:*:*:*:* ≥ 3.14.0 < 3.14.4
cpe:2.3:a:python:python:3.15.0:alpha1:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha2:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha3:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha4:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha5:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha6:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha7:*:*:*:*:*:*

Affected products

Product	Versions
Python Software Foundation · CPython	affected 0 < 3.10.21 ; affected 3.11.0 < 3.11.16 ; affected 3.12.0 < 3.12.14 ; affected 3.13.0 < 3.13.13 ; affected 3.14.0 < 3.14.4 ; affected 3.15.0a1 < 3.15.0a8

References

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD