Python's elementtree C accelerator failed to initialise Expat's hash salt during initialization.
Python's elementtree C accelerator failed to initialise Expat's hash salt during initialization. This could make it easy to conduct denial of service attacks against Expat by constructing an XML document that would cause pathological hash collisions in Expat's internal data structures, consuming large amounts CPU and RAM. The vulnerability exists in Python versions 3.7.0, 3.6.0 through 3.6.6, 3.5.0 through 3.5.6, 3.4.0 through 3.4.9, 2.7.0 through 2.7.15.
- BDU:2018-01554
- DLA-1834-1
- DLA-1835-1
- DSA-4306-1
- DSA-4307-1
- openSUSE-SU-2020:0086-1
- openSUSE-SU-2024:11284-1
- RHSA-2019:1260
- RHSA-2019:2030
- RHSA-2019:3725
- RHSA-2020:1268
- RHSA-2020:1346
- RHSA-2020:1462
- SUSE-SU-2018:3156-1
- SUSE-SU-2019:0482-1
- SUSE-SU-2019:0482-2
- SUSE-SU-2019:2053-1
- SUSE-SU-2019:2053-2
- SUSE-SU-2020:0114-1
- SUSE-SU-2020:2699-1
- Published
- Sep 24, 2018
- Updated
- Jun 16, 2026
- EPSS
- 10.9% · 96th percentile
- CWE
- CWE-335
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Report tools
Action score
33
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 3 / 30 · 10.9%
CNA vs NVD score
- NVD
- 7.5
- CNA · redhat
- 5.3
- 2.2 point gap
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| python | python | cpe:2.3:a:python:python |
| canonical | ubuntu linux | cpe:2.3:o:canonical:ubuntu_linux |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| opensuse | leap | cpe:2.3:o:opensuse:leap |
| redhat | enterprise linux desktop | cpe:2.3:o:redhat:enterprise_linux_desktop |
| redhat | enterprise linux server | cpe:2.3:o:redhat:enterprise_linux_server |
| redhat | enterprise linux workstation | cpe:2.3:o:redhat:enterprise_linux_workstation |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- canonical ubuntu linux12.04
- canonical ubuntu linux14.04
- canonical ubuntu linux16.04
- canonical ubuntu linux18.04
- debian debian linux8.0
- debian debian linux9.0
- fedoraproject fedora30
- opensuse leap15.1
- python python2.7.0 and later · up to 2.7.15 inclusive
- python python3.4.0 and later · up to 3.4.9 inclusive
- python python3.5.0 and later · up to 3.5.6 inclusive
- python python3.6.0 and later · up to 3.6.6 inclusive
- python python3.7.0
- redhat enterprise linux desktop7.0
- redhat enterprise linux server7.0
- redhat enterprise linux workstation7.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.
The Python Project Python
- 3.8, 3.7, 3.6, 3.5, 3.4, 2.7affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | python2 | before 2.7.16-r0 | 2.7.16-r0 |
| Alpine:v3.6 | python3 | before 3.6.8-r0 | 3.6.8-r0 |
| Alpine:v3.7 | python2 | before 2.7.15-r2 | 2.7.15-r2 |
| Debian:11 | python2.7 | before 2.7.15-5 | 2.7.15-5 |
| Debian:8 | python2.7 | before 2.7.9-2+deb8u3 | 2.7.9-2+deb8u3 |
| Debian:8 | python3.4 | before 3.4.2-1+deb8u3 | 3.4.2-1+deb8u3 |
| Debian:9 | python2.7 | before 2.7.13-2+deb9u3 | 2.7.13-2+deb9u3 |
| Debian:9 | python3.5 | before 3.5.3-1+deb9u1 | 3.5.3-1+deb9u1 |
| openSUSE:Leap 15.1 | python3 | before 3.6.10-lp151.6.7.1 | 3.6.10-lp151.6.7.1 |
| openSUSE:Leap 15.1 | python3-base | before 3.6.10-lp151.6.7.1 | 3.6.10-lp151.6.7.1 |
| openSUSE:Tumbleweed | python36 | before 3.6.15-1.1 | 3.6.15-1.1 |
| Red Hat:enterprise_linux:7::client | python | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:enterprise_linux:7::client | python-debug | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:enterprise_linux:7::client | python-debuginfo | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:enterprise_linux:7::client | python-devel | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:enterprise_linux:7::client | python-libs | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:enterprise_linux:7::client | python-test | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:enterprise_linux:7::client | python-tools | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:enterprise_linux:7::client | tkinter | before 0:2.7.5-86.el7 | 0:2.7.5-86.el7 |
| Red Hat:rhel_aus:7.4::server | python | before 0:2.7.5-63.el7_4 | 0:2.7.5-63.el7_4 |
| Red Hat:rhel_aus:7.4::server | python-debug | before 0:2.7.5-63.el7_4 | 0:2.7.5-63.el7_4 |
| Red Hat:rhel_aus:7.4::server | python-debuginfo | before 0:2.7.5-63.el7_4 | 0:2.7.5-63.el7_4 |
| Red Hat:rhel_aus:7.4::server | python-devel | before 0:2.7.5-63.el7_4 | 0:2.7.5-63.el7_4 |
| Red Hat:rhel_aus:7.4::server | python-libs | before 0:2.7.5-63.el7_4 | 0:2.7.5-63.el7_4 |
+65
Same product
python: all recordsOther highest-scoring records for the same primary product.
- CVE-2016-5636Integer overflow in the get_data function in zipimport.c in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 all47Plan
- CVE-2007-4559Directory traversal vulnerability in the (1) extract and (2) extractall functions in the tarfile module in Python allows user-assisted remot47Plan
- CVE-2021-3177Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Pyth46Plan
- CVE-2014-4650The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used for path separators, which al46Plan
- CVE-2018-1000802Python Software Foundation Python (CPython) version 2.7 contains a CWE-77: Improper Neutralization of Special Elements used in a Command ('C45Plan
- CVE-2020-27619In Python 3 through 3.9.0, the Lib/test/multibytecodec_support.py CJK codec tests call eval() on content retrieved via HTTP.42Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| alpine:python2 | 2.7.16-r0 · Alpine:v3.10 | Package registry (OSV) |
| alpine:python3 | 3.6.8-r0 · Alpine:v3.6 | Package registry (OSV) |
| debian:python2.7 | 2.7.15-5 · Debian:11 | Package registry (OSV) |
| debian:python3.4 | 3.4.2-1+deb8u3 · Debian:8 | Package registry (OSV) |
| debian:python3.5 | 3.5.3-1+deb9u1 · Debian:9 | Package registry (OSV) |
| opensuse:python3 | 3.6.10-lp151.6.7.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| opensuse:python3-base | 3.6.10-lp151.6.7.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| opensuse:python36 | 3.6.15-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:python | 0:2.7.5-86.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:python-debuginfo | 0:2.7.5-86.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:python-libs | 0:2.7.5-86.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:python27-python | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-python-debug | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-python-debuginfo | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-python-devel | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-python-jinja2 | 0:2.6-12.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-python-libs | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-python-test | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-python-tools | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| red hat:python27-tkinter | 0:2.7.16-4.el6 · Red Hat:rhel_software_collections:3::el6 | Package registry (OSV) |
| suse:python | 2.6.9-40.21.2 · SUSE:Linux Enterprise Software Development Kit 11 SP4 | Package registry (OSV) |
| suse:python-base | 2.6.9-40.21.1 · SUSE:Linux Enterprise Software Development Kit 11 SP4 | Package registry (OSV) |
| suse:python-doc | 2.6-8.40.21.1 · SUSE:Linux Enterprise Software Development Kit 11 SP4 | Package registry (OSV) |
| suse:python3 | 3.4.6-25.29.1 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:python3-base | 3.4.6-25.29.1 · SUSE:OpenStack Cloud 7 | Package 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.
No dated events beyond publication.
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.
No commit or PR link among the references.
Credits
All researchersFinders, 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.
No nightly-computed relations.
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
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-335 · Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
- www.securityfocus.com/bid/105396
- www.securitytracker.com/id/1041740
- access.redhat.com/errata/RHSA-2019:1260
- access.redhat.com/errata/RHSA-2019:2030
- access.redhat.com/errata/RHSA-2019:3725
- bugs.python.org/issue34623
- bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-14647
- lists.apache.org/thread.html/r1b103833cb5bc8466e24ff0ecc5e75b45a705334ab6a444e64e840a0%40%3Cissues.bookkeeper.apache.org%3E
- lists.debian.org/debian-lts-announce/2019/06/msg00022.html
- lists.debian.org/debian-lts-announce/2019/06/msg00023.html
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RBJCB2HWOJLP3L7CUQHJHNBHLSVOXJE5/
- usn.ubuntu.com/3817-1/
- usn.ubuntu.com/3817-2/
- www.debian.org/security/2018/dsa-4306
- www.debian.org/security/2018/dsa-4307
Vendor advisories and official records. Exploit/PoC links are deliberately left out.