Package Instance

Nokogiri::XML::Schema trusts input by default, exposing risk of an XXE vulnerability
### Description

In Nokogiri versions <= 1.11.0.rc3, XML Schemas parsed by `Nokogiri::XML::Schema`
are **trusted** by default, allowing external resources to be accessed over the
network, potentially enabling XXE or SSRF attacks.

This behavior is counter to
the security policy followed by Nokogiri maintainers, which is to treat all input
as **untrusted** by default whenever possible.

Please note that this security
fix was pushed into a new minor version, 1.11.x, rather than a patch release to
the 1.10.x branch, because it is a breaking change for some schemas and the risk
was assessed to be "Low Severity".

### Affected Versions

Nokogiri `<= 1.10.10` as well as prereleases `1.11.0.rc1`, `1.11.0.rc2`, and `1.11.0.rc3`

### Mitigation

There are no known workarounds for affected versions. Upgrade to Nokogiri
`1.11.0.rc4` or later.

If, after upgrading to `1.11.0.rc4` or later, you wish
to re-enable network access for resolution of external resources (i.e., return to
the previous behavior):

1. Ensure the input is trusted. Do not enable this option
for untrusted input.
2. When invoking the `Nokogiri::XML::Schema` constructor,
pass as the second parameter an instance of `Nokogiri::XML::ParseOptions` with the
`NONET` flag turned off.

So if your previous code was:

``` ruby
# in v1.11.0.rc3 and earlier, this call allows resources to be accessed over the network
# but in v1.11.0.rc4 and later, this call will disallow network access for external resources
schema = Nokogiri::XML::Schema.new(schema)

# in v1.11.0.rc4 and later, the following is equivalent to the code above
# (the second parameter is optional, and this demonstrates its default value)
schema = Nokogiri::XML::Schema.new(schema, Nokogiri::XML::ParseOptions::DEFAULT_SCHEMA)
```

Then you can add the second parameter to indicate that the input is trusted by changing it to:

``` ruby
# in v1.11.0.rc3 and earlier, this would raise an ArgumentError
# but in v1.11.0.rc4 and later, this allows resources to be accessed over the network
schema = Nokogiri::XML::Schema.new(trusted_schema, Nokogiri::XML::ParseOptions.new.nononet)
```

Nokogiri updates packaged libxml2 to 2.13.6 to resolve CVE-2025-24928 and CVE-2024-56171
## Summary

Nokogiri v1.18.3 upgrades its dependency libxml2 to
[v2.13.6](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.13.6).

libxml2 v2.13.6 addresses:

- CVE-2025-24928
  - described at https://gitlab.gnome.org/GNOME/libxml2/-/issues/847
- CVE-2024-56171
   - described at https://gitlab.gnome.org/GNOME/libxml2/-/issues/828

## Impact

### CVE-2025-24928

Stack-buffer overflow is possible when reporting DTD validation
errors if the input contains a long (~3kb) QName prefix.

### CVE-2024-56171

Use-after-free is possible during validation against untrusted
XML Schemas (.xsd) and, potentially, validation of untrusted documents
against trusted Schemas if they make use of `xsd:keyref` in combination
with recursively defined types that have additional identity constraints.

Nokogiri does not check the return value from xmlC14NExecute
Nokogiri's CRuby extension fails to check the return value from `xmlC14NExecute` in the method `Nokogiri::XML::Document#canonicalize` and `Nokogiri::XML::Node#canonicalize`. When canonicalization fails, an empty string is returned instead of raising an exception. This incorrect return value may allow downstream libraries to accept invalid or incomplete canonicalized XML, which has been demonstrated to enable signature validation bypass in SAML libraries.

JRuby is not affected, as the Java implementation correctly raises `RuntimeError` on canonicalization failure.

libxml2 2.9.10 has an infinite loop in a certain end-of-file situation
Nokogiri has backported the patch for CVE-2020-7595 into its vendored version
of libxml2, and released this as v1.10.8

CVE-2020-7595 has not yet been addressed in an upstream libxml2 release, and
so Nokogiri versions <= v1.10.7 are vulnerable.

Duplicate
This advisory duplicates another.

Nokogiri patches vendored libxml2 to resolve multiple CVEs
## Summary

Nokogiri v1.18.9 patches the vendored libxml2 to address
CVE-2025-6021, CVE-2025-6170, CVE-2025-49794, CVE-2025-49795,
and CVE-2025-49796.

## Impact and severity

### CVE-2025-6021

A flaw was found in libxml2's xmlBuildQName function, where integer
overflows in buffer size calculations can lead to a stack-based
buffer overflow. This issue can result in memory corruption or a
denial of service when processing crafted input.

NVD claims a severity of 7.5 High
(CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/17d950ae

### CVE-2025-6170

A flaw was found in the interactive shell of the xmllint command-line
tool, used for parsing XML files. When a user inputs an overly long
command, the program does not check the input size properly, which
can cause it to crash. This issue might allow attackers to run
harmful code in rare configurations without modern protections.

NVD claims a severity of 2.5 Low
(CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L)

Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/5e9ec5c1

### CVE-2025-49794

A use-after-free vulnerability was found in libxml2. This issue
occurs when parsing XPath elements under certain circumstances when
the XML schematron has the <sch:name path="..."/> schema elements.
This flaw allows a malicious actor to craft a malicious XML document
used as input for libxml, resulting in the program's crash using
libxml or other possible undefined behaviors.

NVD claims a severity of 9.1 Critical
(CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H)

Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/81cef8c5

### CVE-2025-49795

A NULL pointer dereference vulnerability was found in libxml2 when
processing XPath XML expressions. This flaw allows an attacker to
craft a malicious XML input to libxml2, leading to a denial of service.

NVD claims a severity of 7.5 High
(CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/62048278

### CVE-2025-49796

A vulnerability was found in libxml2. Processing certain sch:name
elements from the input XML file can trigger a memory corruption
issue. This flaw allows an attacker to craft a malicious XML input
file that can lead libxml to crash, resulting in a denial of service
or other possible undefined behavior due to sensitive data being
corrupted in memory.

NVD claims a severity of 9.1 Critical
(CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H)

Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/81cef8c5

## Affected Versions

- Nokogiri < 1.18.9 when using CRuby (MRI) with vendored libxml2

## Patched Versions

- Nokogiri >= 1.18.9

## Mitigation

Upgrade to Nokogiri v1.18.9 or later.

Users who are unable to upgrade Nokogiri may also choose a more
complicated mitigation: compile and link Nokogiri against patched
external libxml2 libraries which will also address these same issues.

Update bundled libxml2 to v2.10.3 to resolve multiple CVEs
### Summary

Nokogiri v1.13.9 upgrades the packaged version of its dependency libxml2 to
[v2.10.3](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.10.3) from
v2.9.14.

libxml2 v2.10.3 addresses the following known vulnerabilities:

- [CVE-2022-2309](https://nvd.nist.gov/vuln/detail/CVE-2022-2309)
- [CVE-2022-40304](https://nvd.nist.gov/vuln/detail/CVE-2022-40304)
- [CVE-2022-40303](https://nvd.nist.gov/vuln/detail/CVE-2022-40303)

Please note that this advisory only applies to the CRuby implementation of
Nokogiri `< 1.13.9`, and only if the _packaged_ libraries are being used. If
you've overridden defaults at installation time to use _system_ libraries
instead of packaged libraries, you should instead pay attention to your
distro's `libxml2` release announcements.


### Mitigation

Upgrade to Nokogiri `>= 1.13.9`.

Users who are unable to upgrade Nokogiri may also choose a more complicated
mitigation: compile and link Nokogiri against external libraries libxml2
`>= 2.10.3` which will also address these same issues.


### Impact

#### libxml2 [CVE-2022-2309](https://nvd.nist.gov/vuln/detail/CVE-2022-2309)

- **CVSS3 score**: Under evaluation
- **Type**: Denial of service
- **Description**: NULL Pointer Dereference allows attackers to cause a denial
of service (or application crash). This only applies when lxml is used
together with libxml2 2.9.10 through 2.9.14. libxml2 2.9.9 and earlier are not
affected. It allows triggering crashes through forged input data, given a
vulnerable code sequence in the application. The vulnerability is caused by
the iterwalk function (also used by the canonicalize function). Such code
shouldn't be in wide-spread use, given that parsing + iterwalk would usually
be replaced with the more efficient iterparse function. However, an XML
converter that serialises to C14N would also be vulnerable, for example, and
there are legitimate use cases for this code sequence. If untrusted input is
received (also remotely) and processed via iterwalk function, a crash can be
triggered.

Nokogiri maintainers investigated at #2620 and determined this CVE does not
affect Nokogiri users.


#### libxml2 [CVE-2022-40304](https://nvd.nist.gov/vuln/detail/CVE-2022-40304)

- **CVSS3 score**: Unspecified upstream
- **Type**: Data corruption, denial of service
- **Description**: When an entity reference cycle is detected, the entity
content is cleared by setting its first byte to zero. But the entity content
might be allocated from a dict. In this case, the dict entry becomes corrupted
leading to all kinds of logic errors, including memory errors like
double-frees.

See https://gitlab.gnome.org/GNOME/libxml2/-/commit/644a89e080bced793295f61f18aac8cfad6bece2


#### libxml2 [CVE-2022-40303](https://nvd.nist.gov/vuln/detail/CVE-2022-40303)

- **CVSS3 score**: Unspecified upstream
- **Type**: Integer overflow
- **Description**: Integer overflows with XML_PARSE_HUGE

See https://gitlab.gnome.org/GNOME/libxml2/-/commit/c846986356fc149915a74972bf198abc266bc2c0

Nokogiri updates packaged libxml2 to v2.12.7 to resolve CVE-2024-34459
## Summary

Nokogiri v1.16.5 upgrades its dependency libxml2 to
[2.12.7](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.12.7) from 2.12.6.

libxml2 v2.12.7 addresses CVE-2024-34459:

- described at https://gitlab.gnome.org/GNOME/libxml2/-/issues/720
- patched by https://gitlab.gnome.org/GNOME/libxml2/-/commit/2876ac53

## Impact

There is no impact to Nokogiri users because the issue is present only
in libxml2's `xmllint` tool which Nokogiri does not provide or expose.

## Timeline

- 2024-05-13 05:57 EDT, libxml2 2.12.7 release is announced
- 2024-05-13 08:30 EDT, nokogiri maintainers begin triage
- 2024-05-13 10:05 EDT, nokogiri [v1.16.5 is released](https://github.com/sparklemotion/nokogiri/releases/tag/v1.16.5)
  and this GHSA made public

Inefficient Regular Expression Complexity
Nokogiri is an open source XML and HTML library for Ruby. Nokogiri `< v1.13.4` contains an inefficient regular expression that is susceptible to excessive backtracking when attempting to detect encoding in HTML documents. Users are advised to upgrade to Nokogiri `>= 1.13.4`. There are no known workarounds for this issue.

Nokogiri updates packaged libxml2 to v2.13.8 to resolve CVE-2025-32414 and CVE-2025-32415
## Summary

Nokogiri v1.18.8 upgrades its dependency libxml2 to
[v2.13.8](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.13.8).

libxml2 v2.13.8 addresses:

- CVE-2025-32414
  - described at https://gitlab.gnome.org/GNOME/libxml2/-/issues/889
- CVE-2025-32415
  - described at https://gitlab.gnome.org/GNOME/libxml2/-/issues/890

## Impact

### CVE-2025-32414: No impact

In libxml2 before 2.13.8 and 2.14.x before 2.14.2, out-of-bounds
memory access can occur in the Python API (Python bindings) because
of an incorrect return value. This occurs in xmlPythonFileRead and
xmlPythonFileReadRaw because of a difference between bytes and characters.

**There is no impact** from this CVE for Nokogiri users.

### CVE-2025-32415: Low impact

In libxml2 before 2.13.8 and 2.14.x before 2.14.2,
xmlSchemaIDCFillNodeTables in xmlschemas.c has a heap-based buffer
under-read. To exploit this, a crafted XML document must be validated
against an XML schema with certain identity constraints, or a
crafted XML schema must be used.

In the upstream issue, further context is provided by the maintainer:

> The bug affects validation against untrusted XML Schemas (.xsd)
> and validation of untrusted documents against trusted Schemas if
> they make use of xsd:keyref in combination with recursively
> defined types that have additional identity constraints.

MITRE has published a severity score of 2.9 LOW
(CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L) for this CVE.

Nokogiri updates packaged libxml2 to v2.10.4 to resolve multiple CVEs
### Summary

Nokogiri v1.14.3 upgrades the packaged version of its dependency libxml2 to [v2.10.4](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.10.4) from v2.10.3.

libxml2 v2.10.4 addresses the following known vulnerabilities:

- [CVE-2023-29469](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-29469): Hashing of empty dict strings isn't deterministic
- [CVE-2023-28484](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-28484): Fix null deref in xmlSchemaFixupComplexType
- Schemas: Fix null-pointer-deref in xmlSchemaCheckCOSSTDerivedOK

Please note that this advisory only applies to the CRuby implementation of Nokogiri `< 1.14.3`, and only if the _packaged_ libraries are being used. If you've overridden defaults at installation time to use _system_ libraries instead of packaged libraries, you should instead pay attention to your distro's `libxml2` release announcements.


### Mitigation

Upgrade to Nokogiri `>= 1.14.3`.

Users who are unable to upgrade Nokogiri may also choose a more complicated mitigation: compile and link Nokogiri against external libraries libxml2 `>= 2.10.4` which will also address these same issues.


### Impact

No public information has yet been published about the security-related issues other than the upstream commits. Examination of those changesets indicate that the more serious issues relate to libxml2 dereferencing NULL pointers and potentially segfaulting while parsing untrusted inputs.

The commits can be examined at:

- [[CVE-2023-29469] Hashing of empty dict strings isn't deterministic (09a2dd45) · Commits · GNOME / libxml2 · GitLab](https://gitlab.gnome.org/GNOME/libxml2/-/commit/09a2dd453007f9c7205274623acdd73747c22d64)
- [[CVE-2023-28484] Fix null deref in xmlSchemaFixupComplexType (647e072e) · Commits · GNOME / libxml2 · GitLab](https://gitlab.gnome.org/GNOME/libxml2/-/commit/647e072ea0a2f12687fa05c172f4c4713fdb0c4f)
- [schemas: Fix null-pointer-deref in xmlSchemaCheckCOSSTDerivedOK (4c6922f7) · Commits · GNOME / libxml2 · GitLab](https://gitlab.gnome.org/GNOME/libxml2/-/commit/4c6922f763ad958c48ff66f82823ae21f2e92ee6)

Improper Input Validation
In `numbers.c` in libxslt, which is used by nokogiri, an `xsl:number` with certain format strings could lead to an uninitialized read in `xsltNumberFormatInsertNumbers`. This could allow an attacker to discern whether a byte on the stack contains the characters `[AaIi0]`, or any other character.