Medium 4.3Published May 19, 2014

CVE-2013-7040Python 2.7 before 3.4 only uses the last eight bits of the prefix to randomize hash values, which causes it to compute hash values without restricting the ability to trigger hash collisions predictab…

Updated under an hour ago (Nov 2, 2026, 12:20 AM ET)

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It affects apple mac_os_x and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Python 2.7 before 3.4 only uses the last eight bits of the prefix to randomize hash values, which causes it to compute hash values without restricting the ability to trigger hash collisions predictably and makes it easier for context-dependent attackers to cause a denial of service (CPU consumption) via crafted input to an application that maintains a hash table. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-1150.

CVSS: 4.3 MEDIUM (v2.0, NVD)AV:N/AC:M/Au:N/C:N/I:N/A:P
Weakness (CWE): CWE-310
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Modified
Record last updated: Jun 16, 2026
First seen by InfoSec Signals: Nov 1, 2026

Affected products

Affected products

apple mac_os_x apple:mac_os_x	through 10.10.4	NVD
python python python:python	2.7.1; 2.7.1; 2.7.2; 2.7.3; 2.7.4; 2.7.5; 2.7.6; 2.7.7; and 33 more ranges	NVD

References

References

http://bugs.python.org/issue14621
http://lists.apple.com/archives/security-announce/2015/Aug/msg00001.html
http://www.openwall.com/lists/oss-security/2013/12/09/13
http://www.openwall.com/lists/oss-security/2013/12/09/3
http://www.securityfocus.com/bid/64194
https://support.apple.com/kb/HT205031	vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.