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CVE-2026-6019

BaseCookie.js_output() does not neutralize embedded characters

Products / packages Python Software Foundation CPython · Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) · Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) · 3 more

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 23:55:31 UTC
PSF · CVSS:4.0 · 2.1
Assessment vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Severity

low2.1

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

CPython versions less than 3.13.14, 3.14.0a1 to less than 3.14.5rc1, and 3.15.0a1 to less than 3.15.0b1 have a weakness where BaseCookie.js_output() does not neutralize embedded characters. The http.cookies.Morsel.js_output() function returns an inline script snippet and only escapes for JavaScript string context. This may allow HTML parser-sensitive sequences to be injected.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

Python Software Foundation · PSF

CPython

3 ranges
PSF version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

0 → before 3.13.14

python versions

3.14.0a1 → before 3.14.5rc1

python versions

3.15.0a1 → before 3.15.0b1

python versions

unaffected

unknown

Other versions: unaffected

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Siemens · siemens-SADP

SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)

1 range
siemens-SADP version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

V3.1.7 → before *

custom versions

unaffected

unknown

Other versions: unknown

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

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.

References

7 sources
python/cpython · pull request #148848
PatchPSF
mail.python.org/archives/list/security-announce@python.org/thread/IVNWGV2BBNC3RHQAFS22UP4DY56SAXX3/
Vendor advisoryPSF
python/cpython · commit 76b3923
PatchPSF
python/cpython · commit 3c59b8b
PatchPSF
python/cpython · commit f795e04
PatchPSF
python/cpython · issues/90309
Source referencePSF
View 1 more references
cert-portal.siemens.com/productcert/html/ssa-457936.html
Source referencesiemens-SADP

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-6019

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-150 ↗

CWE-150 Improper neutralization of escape, meta, or control sequences

PSF

Related →
Contributing organizations · 3
PSF

Assigning organization

2026-06-10
CISA-ADP

Additional data publisher

2026-04-22
siemens-SADP

Additional data publisher

2026-11-10

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.