Package Instance

Vulnerabilities in libxml2
The version of libxml2 packaged with Nokogiri contains several vulnerabilities. Nokogiri has mitigated these issues by upgrading to libxml It was discovered that a type confusion error existed in libxml2. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code. (CVE-2017-0663) It was discovered that libxml2 did not properly validate parsed entity references. An attacker could use this to specially construct XML data that could expose sensitive information. (CVE-2017-7375) It was discovered that a buffer overflow existed in libxml2 when handling HTTP redirects. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code. (CVE-2017-7376) Marcel Böhme and Van-Thuan Pham discovered a buffer overflow in libxml2 when handling elements. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code. (CVE-2017-9047) Marcel Böhme and Van-Thuan Pham discovered a buffer overread in libxml2 when handling elements. An attacker could use this to specially construct XML data that could cause a denial of service. (CVE-2017-9048) Marcel Böhme and Van-Thuan Pham discovered multiple buffer overreads in libxml2 when handling parameter-entity references. An attacker could use these to specially construct XML data that could cause a denial of service. (CVE-2017-9049, CVE-2017-9050)

Nokogiri update packaged libxml2 to v2.12.5 to resolve CVE-2024-25062
## Summary

Nokogiri upgrades its dependency libxml2 as follows:
- Nokogiri v1.15.6 upgrades libxml2 to [2.11.7](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.11.7) from 2.11.6
- Nokogiri v1.16.2 upgrades libxml2 to [2.12.5](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.12.5) from 2.12.4

libxml2 v2.11.7 and v2.12.5 address the following vulnerability:

- CVE-2024-25062 / https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-25062
  - described at https://gitlab.gnome.org/GNOME/libxml2/-/issues/604
  - patched by https://gitlab.gnome.org/GNOME/libxml2/-/commit/92721970

Please note that this advisory only applies to the CRuby implementation of Nokogiri, 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.

JRuby users are not affected.

## Mitigation

Upgrade to Nokogiri `~> 1.15.6` or `>= 1.16.2`.

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.

## Impact

From the CVE description, this issue applies to the `xmlTextReader` module (which underlies `Nokogiri::XML::Reader`):

> When using the XML Reader interface with DTD validation and XInclude expansion enabled, processing crafted XML documents can lead to an xmlValidatePopElement use-after-free.

## Timeline

- 2024-02-04 10:35 EST - this GHSA is drafted without complete details about when the upstream issue was introduced; a request is made of libxml2 maintainers for more detailed information
- 2024-02-04 10:48 EST - updated GHSA to reflect libxml2 maintainers' confirmation of affected versions
- 2024-02-04 11:54 EST - v1.16.2 published, this GHSA made public
- 2024-02-05 10:18 EST - updated with MITRE link to the CVE information, and updated "Impact" section
- 2024-03-16 09:03 EDT - v1.15.6 published (see discussion at https://github.com/sparklemotion/nokogiri/discussions/3146), updated mitigation information
- 2024-03-18 22:12 EDT - update "affected products" range with v1.15.6 information

Upstream libxslt vulnerabilities
The `xsltAddTextString` function in `transform.c` in libxslt, as used by nokogiri, lacks a check for integer overflow during a size calculation, which allows a remote attacker to perform an out-of-bounds memory write via a crafted HTML page.

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


### References

- [libxml2 release notes](https://gitlab.gnome.org/GNOME/libxml2/-/releases)
- [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)

Nokogiri has a vulnerability allowing arbitrary execution of code
    if a certain function is used.

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.

## References

- https://github.com/sparklemotion/nokogiri/pull/3526
- https://nvd.nist.gov/vuln/detail/CVE-2025-6021
- https://nvd.nist.gov/vuln/detail/CVE-2025-6170
- https://nvd.nist.gov/vuln/detail/CVE-2025-49794
- https://nvd.nist.gov/vuln/detail/CVE-2025-49795
- https://nvd.nist.gov/vuln/detail/CVE-2025-49796

Multiple vulnerabilities have been found in libxml2, the worst of
    which could result in a Denial of Service condition.

Improper Restriction of XML External Entity Reference
Nokogiri is a Rubygem providing HTML, XML, SAX, and Reader parsers with XPath and CSS selector support. In Nokogiri v1.12.4, on JRuby only, the SAX parser resolves external entities by default. Users of Nokogiri on JRuby who parse untrusted documents using any of these classes are affected: Nokogiri::XML::SAX::Parse, Nokogiri::HTML4::SAX::Parser or its alias Nokogiri::HTML::SAX::Parser, Nokogiri::XML::SAX::PushParser, and Nokogiri::HTML4::SAX::PushParser or its alias Nokogiri::HTML::SAX::PushParser. JRuby users should upgrade to Nokogiri.

Improper Input Validation
In `numbers.c` in libxslt, which is used by nokogiri, a type holding grouping characters of an `xsl:number` instruction was too narrow and an invalid character/length combination could be passed to `xsltNumberFormatDecimal`, leading to a read of uninitialized stack data.