GHSA-v2fc-qm4h-8hqv CVE-2026-79771
Nokogiri XSLT transform has a memory leak
- Severity
- 6.9 / 10
- Medium · CVSS 4.0
- Exploit chance (EPSS)
- 0.42%
- Chance of exploitation in the next 30 days. Higher than 36.61% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-401 Missing Release of Memory after Effective Lifetime
- Fix
1.19.3- Upgrade nokogiri to this version or later
Description
Summary
Nokogiri's Nokogiri::XSLT::Stylesheet#transform leaks a small heap allocation when passed a Ruby string parameter containing a null byte.
For applications that pass attacker-controlled input through XSLT.transform parameters, this may be a vector for a denial of service attack against long-running processes.
Mitigation
Upgrade to Nokogiri >= 1.19.3.
Users may also be able to mitigate this issue without upgrading by validating untrusted transform parameters before passing them to Nokogiri::XSLT::Stylesheet#transform.
Severity
The Nokogiri maintainers have evaluated this as Moderate Severity, CVSS 5.3.
Each leaked allocation is approximately 24–32 bytes, so meaningful memory growth requires sustained attacker-controlled traffic at high call rates. The bug does not cause memory corruption, information disclosure, or any change in the behavior of the transform itself, and the string-handling exception is raised as expected.
Applications that do not pass raw attacker-controlled bytes to XSLT parameters are unlikely to be affected in practice.
Resources
Credit
This vulnerability was responsibly reported by @Captainjack-kor.
Affected versions
RubyGems
| Package | Vulnerable | Fixed in |
|---|---|---|
| nokogiri | < 1.19.3 |
1.19.3 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
nokogiri RubyGems → 1.19.3
- bundler
bundle update nokogiri # Gemfile: gem "nokogiri", ">= 1.19.3"
Severity breakdown
CVSS 4.0 6.9
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- Low
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Not defined
- Scope
- X
CVSS 3.1 5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Weakness
CWE-401: Missing Release of Memory after Effective Lifetime
The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
How to prevent it
- Implementation: Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone. For example, glibc in Linux provides protection against free of invalid pointers. When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391]. To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.
- Architecture and Design: Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Architecture and Design, Build and Compilation: Consider using the Boehm-Demers-Weiser garbage collector (bdwgc), which can help avoid leaks.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-phwj-rprq-35pp Nokogiri: Possible Use-After-Free when setting an attribute value via `Nokogiri::XML::Attr#value=` or `#content=` | High | Also affects nokogiri |
| GHSA-wfpw-mmfh-qq69 Nokogiri: Possible Use-After-Free in XInclude Processing | Low | Also affects nokogiri |
| GHSA-p67v-3w7g-wjg7 Nokogiri: Possible Use-After-Free when directly using `NokogirI::XML::XPathContext` beyond document lifetime | Medium | Also affects nokogiri |
| GHSA-wjv4-x9w8-wm3h Nokogiri: Possible Use-After-Free when setting `Document#root=` to an invalid node type | Medium | Also affects nokogiri |
| GHSA-5prr-v3j2-97mh Nokogiri: Possible Out-of-Bounds Read in `Nokogiri::XML::NodeSet#[]` | High | Also affects nokogiri |
| GHSA-9cv2-cfxc-v4v2 Nokogiri: Null Pointer Dereference calling methods on uninitialized wrapper classes | High | Also affects nokogiri |
| GHSA-8678-w3jw-xfc2 Nokogiri: XML::Schema on JRuby allows network requests when NONET is set, bypassing CVE-2020-26247 | Low | Also affects nokogiri |
| GHSA-5v8h-3h3q-446p Nokogiri: Possible Use-After-Free when `Nokogiri::XML::Document#encoding=` raises an exception | High | Also affects nokogiri |
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