CVE-2026-7210Network attack vector

Denial of service via low-entropy XML hash salt

Published May 11, 2026 · Updated May 11, 2026

Hash-flooding denial of service in CPython's XML parsers allows remote attackers to exhaust CPU by submitting crafted XML documents. The pyexpat and _elementtree bindings call XML_SetHashSalt with only 4 to 8 bytes of the process hash secret instead of a 16-byte salt. Exploitation requires an application to parse attacker-controlled XML with either module; confidentiality and integrity are unaffected.

CVSS severity7.5
High
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Hash-flooding denial of service in CPython's XML parsers allows remote attackers to exhaust CPU by submitting crafted XML documents. The pyexpat and _elementtree bindings call XML_SetHashSalt with only 4 to 8 bytes of the process hash secret instead of a 16-byte salt. Exploitation requires an application to parse attacker-controlled XML with either module; confidentiality and integrity are unaffected.

The record

CVE
CVE-2026-7210
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Python Software Foundation
Product
CPython
Classifications
CWE-331, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.15.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Python Software Foundation · CPythonversion=0 <3.15.0

Published CVSS scores

6.3Python Software FoundationCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-331Insufficient Entropy
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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