BaseCookie.js_output() does not neutralize embedded characters
http.cookies.Morsel.js_output() returns an inline <script> snippet and only escapes " for JavaScript string context. It does not neutralize the HTML parser-sensitive sequence </script> inside the generated script element. Mitigation base64-encodes the cookie value to disallow escaping using cookie value.
- BDU:2026-13663
- ALSA-2026:28247
- ALSA-2026:28581
- openSUSE-SU-2026:10647-1
- openSUSE-SU-2026:10648-1
- openSUSE-SU-2026:10667-1
- openSUSE-SU-2026:11068-1
- openSUSE-SU-2026:11100-1
- openSUSE-SU-2026:11181-1
- openSUSE-SU-2026:21459-1
- RHSA-2026:22952
- RHSA-2026:28247
- RHSA-2026:28581
- RHSA-2026:32980
- RHSA-2026:32997
- RHSA-2026:33885
- RHSA-2026:57660
- RHSA-2026:58420
- RLSA-2026:28247
- RLSA-2026:28581
- Published
- Apr 22, 2026
- Updated
- Jul 27, 2026
- EPSS
- 0.6% · 46th percentile
- CWE
- CWE-150
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
8
Monitor
Low priority for now.
- CVSS
- 8 / 40 · 2.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.6%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · PSF
- 2.1
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| python | python | cpe:2.3:a:python:python |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- python pythonbefore 3.13.14
- python python3.14.0 and later · up to 3.14.4 inclusive
- python python3.15.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (PSF). Independent of NVD's CPE analysis and usually ahead of it.
Python Software Foundation CPython
- before 3.13.14affected · python
- 3.14.0a1 and later · before 3.14.5rc1affected · python
- 3.15.0a1 and later · before 3.15.0b1affected · python
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | python3.14 | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-debug | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-devel | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-debug | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-devel | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-idle | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-libs | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-test | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-tkinter | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-idle | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-libs | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-test | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:10 | python3.14-tkinter | before 3.14.5-1.el10_2 | 3.14.5-1.el10_2 |
| AlmaLinux:9 | python3.14 | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-debug | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-devel | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-freethreading | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-freethreading-debug | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-freethreading-devel | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-freethreading-idle | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-freethreading-libs | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-freethreading-test | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
| AlmaLinux:9 | python3.14-freethreading-tkinter | before 3.14.5-1.el9_8 | 3.14.5-1.el9_8 |
+88
Same product
python: all recordsOther highest-scoring records for the same primary product.
- CVE-2016-5636Integer overflow in the get_data function in zipimport.c in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 all47Plan
- CVE-2007-4559Directory traversal vulnerability in the (1) extract and (2) extractall functions in the tarfile module in Python allows user-assisted remot47Plan
- CVE-2021-3177Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Pyth46Plan
- CVE-2014-4650The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used for path separators, which al46Plan
- CVE-2018-1000802Python Software Foundation Python (CPython) version 2.7 contains a CWE-77: Improper Neutralization of Special Elements used in a Command ('C45Plan
- CVE-2020-27619In Python 3 through 3.9.0, the Lib/test/multibytecodec_support.py CJK codec tests call eval() on content retrieved via HTTP.42Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Python Software Foundation CPython | 3.13.14 | Vendor (CNA) |
| Python Software Foundation CPython | 3.14.5rc1 | Vendor (CNA) |
| Python Software Foundation CPython | 3.15.0b1 | Vendor (CNA) |
| almalinux:python3.14 | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-debug | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-devel | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-freethreading | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-freethreading-debug | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-freethreading-devel | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-freethreading-idle | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-freethreading-libs | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-freethreading-test | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-freethreading-tkinter | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-idle | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.14-libs | 3.14.5-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| debian:python3.13 | 3.13.5-2+deb13u2 · Debian:13 | Package registry (OSV) |
| debian:python3.14 | 3.14.5~rc1-1 · Debian:14 | Package registry (OSV) |
| opensuse:python3 | 3.13.14-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:python310 | 3.10.20-6.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python311 | 3.11.15-6.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python312 | 3.12.13-6.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python313 | 3.13.13-2.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python313-core | 3.13.14-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:python313-documentation | 3.13.14-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:python313-nogil | 3.13.14-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:python313-nogil-nogil-core | 3.13.14-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:python314 | 3.14.6-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python315 | 3.15.0~a8-3.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:python-unversioned-command | 0:3.14.5-2.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:python3 | 0:3.14.5-2.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
+23
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- Administrator privileges are required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-150 · Improper Neutralization of Escape, Meta, or Control SequencesCVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/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-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/python/cpython/commit/3c59b8b53fc75c7f9578d16fb8201ceb43e8f76c
- github.com/python/cpython/commit/76b3923d688c0efc580658476c5f525ec8735104
- github.com/python/cpython/commit/f795e042043dfe26c42e1971d4502c1cdc4c65b8
- github.com/python/cpython/pull/148848
- mail.python.org/archives/list/security-announce@python.org/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.