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CVE.org (no NVD analysis yet)· CNA GitHub_M

CVE-2026-97689: urllib3: HTTPResponse.stream()/read_chunked() buffers an unbounded chunk-size line into memory

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.33% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: urllib3 urllib3 2.8.0; azl3 python-urllib3 2.0.7-6 on Azure Linux 3.0 2.0.7-7.

Low priority for now. Upgrade to urllib3 urllib3 2.8.0; azl3 python-urllib3 2.0.7-6 on Azure Linux 3.0 2.0.7-7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

urllib3 is an HTTP client library for Python. From 1.10.3 until 2.8.0, the HTTPResponse.read_chunked and HTTPResponse.stream methods can allocate unbounded memory because the streaming chunk parser buffers the chunk-size field until newline or EOF without a length bound. The trigger is that a malicious server returns Transfer-Encoding: chunked followed by a very long run of bytes without a newline. The attack mechanism is that a malicious HTTP server sends a very long unterminated chunk-size line. The impact is that unbounded memory allocation can exhaust the client process. This issue is fixed in version 2.8.0.

HighCVSS 8.9 · v4.0—No exploit Fix available
Published
Sep 29, 2026
Updated
Oct 13, 2026
EPSS
0.3% · 26th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
8.9
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-97689

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
pythonurllib3

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • python urllib31.10.3 and later · before 2.8.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • urllib3 urllib3

    • >= 1.10.3, < 2.8.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10python3-urllib3before 1.26.19-4.el10_2.21.26.19-4.el10_2.2
AlmaLinux:10python3.14-urllib3before 2.6.3-2.el10_2.62.6.3-2.el10_2.6
AlmaLinux:8python3-urllib3before 1.24.2-11.el8_101.24.2-11.el8_10
AlmaLinux:8python3.12-urllib3before 1.26.19-5.el8_101.26.19-5.el8_10
AlmaLinux:9python3-urllib3before 1.26.5-8.el9_8.21.26.5-8.el9_8.2
AlmaLinux:9python3.12-urllib3before 1.26.19-3.el9_8.21.26.19-3.el9_8.2
AlmaLinux:9python3.14-urllib3before 2.6.3-2.el9_8.62.6.3-2.el9_8.6
Debian:12python-urllib3from 0—
Debian:14python-urllib3before 2.8.0-12.8.0-1
openSUSE:Leap 16.0python-urllib3before 2.5.0-160000.8.12.5.0-160000.8.1
openSUSE:Tumbleweedpython-urllib3before 2.8.0-1.12.8.0-1.1
openSUSE:Tumbleweedpython-urllib3_1before 1.26.20-8.11.26.20-8.1
PyPIurllib3from 1.10.3 · before 2.8.02.8.0
Red Hat:enterprise_linux:10.2python3.14-urllib3before 0:2.6.3-2.el10_2.60:2.6.3-2.el10_2.6
Red Hat:enterprise_linux:9::appstreampython3.14-urllib3before 0:2.6.3-2.el9_8.60:2.6.3-2.el9_8.6
Red Hat:hummingbird:1python-urllib3before 0:2.8.0-1.hum10:2.8.0-1.hum1
Red Hat:hummingbird:1python3-urllib3before 0:2.8.0-1.hum10:2.8.0-1.hum1
Red Hat:hummingbird:1python3-urllib3+brotlibefore 0:2.8.0-1.hum10:2.8.0-1.hum1
Red Hat:hummingbird:1python3-urllib3+h2before 0:2.8.0-1.hum10:2.8.0-1.hum1
Red Hat:hummingbird:1python3-urllib3+socksbefore 0:2.8.0-1.hum10:2.8.0-1.hum1
Red Hat:hummingbird:1python3-urllib3+zstdbefore 0:2.8.0-1.hum10:2.8.0-1.hum1
Rocky Linux:10python-urllib3before 0:1.26.19-4.el10_2.20:1.26.19-4.el10_2.2
Rocky Linux:10python3.14-urllib3before 0:2.6.3-2.el10_2.60:2.6.3-2.el10_2.6
Rocky Linux:8python-urllib3before 0:1.24.2-11.el8_100:1.24.2-11.el8_10

+9

Same product

python: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-20060urllib3 before version 1.23 does not remove the Authorization HTTP header when following a cross-origin redirect (i.e., a redirect that diff
    40Plan
  • CVE-2026-21441urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API)
    36Monitor
  • CVE-2026-44432urllib3: Decompression-bomb safeguards bypassed in parts of the streaming API
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-44431May 13, 2026 · urllib3: Sensitive headers forwarded across origins in proxied low-level redirects
    32Monitor
  • ← EarlierCVE-2026-97687Sep 29, 2026 · urllib3: HTTPS proxy TLS configuration may be ignored or overridden
    30Monitor
  • ← EarlierCVE-2026-97688Sep 29, 2026 · urllib3: Chunked Deflate streaming can enter an infinite loop
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
urllib3 urllib32.8.0 · descriptionVendor (CNA)
azl3 python-urllib3 2.0.7-6 on Azure Linux 3.02.0.7-7 · Release NotesMicrosoft (MSRC)
almalinux:python3-urllib31.26.19-4.el10_2.2 · AlmaLinux:10Package registry (OSV)
almalinux:python3.12-urllib31.26.19-3.el9_8.2 · AlmaLinux:9Package registry (OSV)
almalinux:python3.14-urllib32.6.3-2.el9_8.6 · AlmaLinux:9Package registry (OSV)
debian:python-urllib32.8.0-1 · Debian:14Package registry (OSV)
opensuse:python-urllib32.8.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:python-urllib3_11.26.20-8.1 · openSUSE:TumbleweedPackage registry (OSV)
PyPI:urllib32.8.0Package registry (OSV)
red hat:python-urllib30:2.8.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3-urllib30:2.8.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3-urllib3+brotli0:2.8.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3-urllib3+h20:2.8.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3-urllib3+socks0:2.8.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3-urllib3+zstd0:2.8.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3.14-urllib30:2.6.3-2.el9_8.6 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
rocky linux:python-urllib30:1.26.19-4.el10_2.2 · Rocky Linux:10Package registry (OSV)
rocky linux:python-urllib30:1.26.5-8.el9_8.2 · Rocky Linux:9Package registry (OSV)
rocky linux:python3.12-urllib30:1.26.19-3.el9_8.2 · Rocky Linux:9Package registry (OSV)
rocky linux:python3.14-urllib30:2.6.3-2.el9_8.6 · Rocky Linux:9Package registry (OSV)
suse:python-urllib32.5.0-160000.8.1 · SUSE:Linux Micro 6.2Package registry (OSV)
suse:python-urllib3_11.26.18-150600.3.14.1 · SUSE:Linux Enterprise Module for Python 3 15 SP7Package registry (OSV)

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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 4, 2026+35 d
EPSS, last 120 days

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 researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2025-66418298 days aparturllib3 allows an unbounded number of links in the decompression chain
    35Monitor

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.
  • No account or password is 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
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-770 · Allocation of Resources Without Limits or Throttling

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/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.

Change log

  1. Exploit maturity— → none
  2. Fix✗ → ✓
  3. SSVC exploitation— → none

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records