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No exploitation reportedFix available

CVE-2025-13836

No exploitation reported by the sources we read.

  • Published2025-12-01
  • Fixed in3.14.1 · 3.13.11 · 3.12.13 · 3.11.15 · 3.10.20
  • WeaknessCWE-400

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

When reading an HTTP response from a server, if no read amount is specified, the default behavior will be to use Content-Length. This allows a malicious server to cause the client to read large amounts of data into memory, potentially causing OOM or other DoS.

Timeline

dates in UTC
  1. 2025-12-0118:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2025-13836?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2025-13836?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD
Python
BranchAffectedFixed in
3.14≥ 3.14.0, < 3.14.13.14.1
3.13≥ 3.13.0, < 3.13.113.13.11
3.12≥ 3.12.0, < 3.12.133.12.13
3.11≥ 3.11.0, < 3.11.153.11.15
3.10< 3.10.203.10.20
3.14= 3.14.0no fix published
3.15= 3.15.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • python-unversioned-commandAlmaLinux:10all versions · fixed in 3.12.12-3.el10_1
  • python3.11AlmaLinux:9all versions · fixed in 3.11.13-5.el9_7and 6 other packages
  • python3.11AlmaLinux:8all versions · fixed in 3.11.13-4.el8_10and 7 other packages
  • python3.12AlmaLinux:9all versions · fixed in 3.12.12-4.el9_7and 6 other packages
  • python3.12AlmaLinux:8all versions · fixed in 3.12.12-2.el8_10and 7 other packages

Vendor advisories

  • RHSA-2026:4943 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Update Infrastructure 5.1 security update

Full record on NVD

Fix

  1. Update Python to 3.14.1 · 3.13.11 · 3.12.13 · 3.11.15 · 3.10.20
  2. Vendor fix Red Hat Product Security RHSA-2026:4943 · 1 productThe container images provided by this release, apart from the installer, should be deployed using rhui-installer utility. See the official documentation for more details.
  3. Workaround from the vendor Red Hat Product Security RHSA-2026:4943 · 4 productsSince this vulnerability is triggered when no read amount is specified and the client defaults to using the potentially malicious Content-Length header, developers can mitigate this issue in their code by always imposing an explicit, safe limit on data reads. Applications using the http.client.HTT…

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionnone2025-12-01
  • OpenCVESSVC decisionnone—
  • CNACVSS 4.06.3read 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • CISA-ADPweakness (CWE)CWE-4002025-12-01
  • FIRST EPSSEPSS score1.6 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/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
Published
2025-12-01
Last Modified
2026-09-03
NVD status
Analyzed

Frequently asked questions

What is CVE-2025-13836?

When reading an HTTP response from a server, if no read amount is specified, the default behavior will be to use Content-Length. This allows a malicious server to cause the client to read large amounts of data into memory, potentially causing OOM or other DoS.

Is CVE-2025-13836 actively exploited?

Active exploitation of CVE-2025-13836 has not been confirmed. Its EPSS score was 1.6% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-13836?

CVE-2025-13836 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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