CVE-2013-7040
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…
- 4.3MediumCVSS base score
- 3.1%Exploitation in 30 daysEPSS · top 12% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By mitre
- 5 months later
· 5 months later
Published
- 10 years later
· 10 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 2.0 | Medium4.3 | AV:N/AC:M/Au:N/C:N/I:N/A:P |
- EPSS (exploitation in 30 days)
- 3.1% · top 12% of all CVEs (10 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.
Affected products
n/a
- affected n/a
References
6
- 64194 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
- [oss-security] 20131209 Re: CPython hash secret can be recoved remotely (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- [oss-security] 20131209 CPython hash secret can be recoved remotely (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- APPLE-SA-2015-08-13-2 (opens in a new tab)vendor-advisoryx_refsource_APPLEx_transferred
- http://bugs.python.org/issue14621 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://support.apple.com/kb/HT205031 (opens in a new tab)x_refsource_CONFIRMx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2013-6840 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2013-7040)Record last updated .