CVE-2018-7753
Bleach URI Scheme Restriction Bypass
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
9.8
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
CVE-2018-7753- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-20
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
CVE-2018-7753- Updated
- 2026-11-02
EUVDEUVD-2018-0026 No score
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
EUVD-2018-0026- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-m9mq-p2f9-cfqv
9.3
Bleach URI Scheme Restriction Bypass
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
GHSA-m9mq-p2f9-cfqv- CVSS 4.0
- 9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-20
- Updated
- 2026-11-02
OSV
9.8
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
CVE-2018-7753- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2018-7753
9.8
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
DEBIAN-CVE-2018-7753- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Show 7 moreShow less
OSVGHSA-m9mq-p2f9-cfqv
9.3
Bleach URI Scheme Restriction Bypass
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
GHSA-m9mq-p2f9-cfqv- CVSS 4.0
- 9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-20
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2018-7753
9.8
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
UBUNTU-CVE-2018-7753- CVSS 3.0
- 9.8 Critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVopenSUSE-SU-2024:11219-1 No score
python36-bleach-3.3.0-1.4 on GA media
These are all security issues fixed in the python36-bleach-3.3.0-1.4 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:11219-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:14134-1 No score
python310-bleach-6.1.0-1.5 on GA media
These are all security issues fixed in the python310-bleach-6.1.0-1.5 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:14134-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:11323-1 No score
python313-bleach-6.4.0-1.1 on GA media
These are all security issues fixed in the python313-bleach-6.4.0-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:11323-1- Updated
- 2026-11-02
OSVPYSEC-2018-51 No score
An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.
- Record
PYSEC-2018-51- Updated
- 2026-11-02
OSVUSN-8077-1 No score
python-bleach vulnerabilities
It was discovered that Bleach did not properly sanitize URI attributes containing character entities. An attacker could possibly use this issue to construct a URI with a disallowed scheme that would bypass sanitization, leading to cross-site scripting. This issue only affected Ubuntu 18.04 LTS. (CVE-2018-7753)
Yaniv Nizry discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing HTML with the noscript tag and a raw tag in the allowed tags list. An attacker could possibly use this issue to inject malicious content, leading to cross-site scripting. This issue only affected Ubuntu 18.04 LTS. (CVE-2020-6802)
Yaniv Nizry discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing HTML with RCDATA together with svg or math tags in the allowed tags list. An attacker could possibly use this issue to inject malicious content, leading to cross-site scripting. (CVE-2020-6816)
It was discovered that Bleach incorrectly handled parsing of style attributes when sanitizing HTML. An attacker could possibly use this issue to perform a regular expression denial of service, leading to excessive resource consumption. (CVE-2020-6817)
Yaniv Nizry and Michał Bentkowski discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing HTML with certain combinations of allowed tags. An attacker could possibly use this issue to inject malicious content, leading to cross-site scripting. (CVE-2021-23980)
- Record
USN-8077-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
bleachPyPI |
2.1.0 up to 2.1.3 | 2.1.3 |
python-bleachDebian:12 |
before 2.1.3-1 | 2.1.3-1 |
python-bleachDebian:13 |
before 2.1.3-1 | 2.1.3-1 |
python-bleachDebian:14 |
before 2.1.3-1 | 2.1.3-1 |
bleachPyPI |
2.1.0 up to 2.1.3, plus listed versions 2.12.1.12.1.2 |
2.1.3 |
bleachPyPI |
2.1 up to 2.1.3, plus listed versions 2.1.12.1.2 |
2.1.3 |
python-bleachUbuntu:Pro:18.04:LTS |
before 2.1.2-1ubuntu0.1~esm1, plus listed versions 2.0-12.1.2-1 |
2.1.2-1ubuntu0.1~esm1 |
python-bleachUbuntu:Pro:16.04:LTS |
before 1.4.2-1ubuntu0.1~esm1, plus listed versions 1.4-11.4.2-1 |
1.4.2-1ubuntu0.1~esm1 |
python-bleachUbuntu:Pro:20.04:LTS |
before 3.1.1-1ubuntu0.1~esm1, plus listed versions 3.1.0-13.1.0-23.1.1-1 |
3.1.1-1ubuntu0.1~esm1 |
python-bleachopenSUSE:Tumbleweed From an advisory covering 5 CVEs |
before 6.1.0-1.5 | 6.1.0-1.5 |
python-bleachopenSUSE:Tumbleweed From an advisory covering 5 CVEs |
before 6.4.0-1.1 | 6.4.0-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2018-7753 is a critical vulnerability (CVSS 9.8) in Mozilla Bleach, published March 7, 2018. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.17%, the 82nd percentile. Fixed in bleach 2.1.3.
References
github.com/mozilla/bleach/releases/tag/v2.1.3
github.com/mozilla/bleach/commit/c5df5789ec3471a31311f42c2d19fc2cf21b35ef
bugs.debian.org/892252
nvd.nist.gov/vuln/detail/CVE-2018-7753
github.com/pypa/advisory-database/tree/main/vulns/bleach/PYSEC-2018-51.yaml
github.com/advisories/GHSA-m9mq-p2f9-cfqv
Show 15 moreShow less
security-tracker.debian.org/tracker/CVE-2018-7753
github.com/mozilla/bleach
ubuntu.com/security/CVE-2018-7753
github.com/mozilla/bleach/pull/356
cve.org/CVERecord?id=CVE-2018-7753
ubuntu.com/security/notices/USN-8077-1
ubuntu.com/security/CVE-2020-6802
ubuntu.com/security/CVE-2020-6816
ubuntu.com/security/CVE-2020-6817
ubuntu.com/security/CVE-2021-23980
suse.com/security/cve/CVE-2018-7753
suse.com/security/cve/CVE-2020-6802
suse.com/security/cve/CVE-2020-6816
suse.com/security/cve/CVE-2020-6817
suse.com/security/cve/CVE-2021-23980