# CVE-2026-79772: Nokogiri before 1.19.1 Unchecked Return Value canonicalize

> Attackers can bypass SAML signature validation by exploiting unchecked return values in Nokogiri's canonicalization method, accepting invalid XML as valid.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-79772, CLEANSTART-2026-YY44822, DEBIAN-CVE-2026-79772, GHSA-wx95-c6cv-8532, MINI-4549-7qmf-g294, MINI-5chf-488p-2rvj, MINI-c83f-g7m4-398w, MINI-hm8p-w4ch-84c7, MINI-hrmv-jx4w-4rcp, MINI-hvvc-hm27-68r9, MINI-j7c6-m5gc-pfjm, MINI-xvfq-jxw4-mjvw, UBUNTU-CVE-2026-79772

## What is CVE-2026-79772?

CVE-2026-79772 is a medium-severity vulnerability in sparklemotion nokogiri, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Nokogiri versions before 1.19.1 fail to check the return value from xmlC14NExecute in the canonicalize method, returning an empty string on failure instead of raising an exception. Attackers can exploit this to bypass signature validation in downstream SAML libraries by providing invalid canonicalized XML that is incorrectly accepted as valid.

Weakness: CWE-252 (Unchecked Return Value)

## Which versions are affected by CVE-2026-79772?

2 open source packages ship an affected version, including nokogiri. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nokogiri` | RubyGems | From 1.5.1 | 1.19.1 |
| `nokogiri` | RubyGems | From 1.5.1 | 1.19.1 |

Products: Nokogiri Nokogiri.

## How do I fix CVE-2026-79772?

Upgrade nokogiri to 1.19.1 or later.

## Is CVE-2026-79772 being exploited?

There is no known exploitation of CVE-2026-79772 in the wild and no public exploit code.

## Other vulnerabilities in sparklemotion nokogiri

- [CVE-2026-79770](https://insights.sbomify.com/CVE-2026-79770/): Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer (high 8.7)
- [CVE-2022-23476](https://insights.sbomify.com/CVE-2022-23476/): Unchecked return value from xmlTextReaderExpand in Nokogiri (high 7.5)
- [CVE-2021-41098](https://insights.sbomify.com/CVE-2021-41098/): Improper Restriction of XML External Entity Reference (XXE) in Nokogiri on JRuby (high 7.5)
- [CVE-2012-6685](https://insights.sbomify.com/CVE-2012-6685/): Nokogiri is vulnerable to XML External Entity (XXE) attack (high 7.5)
- [CVE-2026-79771](https://insights.sbomify.com/CVE-2026-79771/): Nokogiri before 1.19.3 Memory Leak via XSLT Transform (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-79772 and fix it if it is affected.

What it is: CVE-2026-79772 is a medium-severity vulnerability in sparklemotion nokogiri, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-79772 in the wild and no public exploit code.

Affected packages and fixed versions:
- nokogiri (RubyGems): affected from 1.5.1; fixed in 1.19.1
- nokogiri (RubyGems): affected from 1.5.1; fixed in 1.19.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-79772/ (Markdown: https://insights.sbomify.com/CVE-2026-79772/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-79772
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-79772
- OSV: https://osv.dev/vulnerability/CVE-2026-79772

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-79772/
Summaries are generated and may contain mistakes; the official description above is the record.