# CVE-2026-104774: OWASP Coraza WAF: jsDecode Off-by-One in Octal Escape Handling Enables WAF Bypass

> An off-by-one error in OWASP Coraza WAF's jsDecode transformation allows attackers to bypass security rules using JavaScript octal escapes.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-pc5q-qfxp-ggqv, GO-2026-6696

## What is CVE-2026-104774?

CVE-2026-104774 is a medium-severity vulnerability in corazawaf coraza, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OWASP Coraza WAF is a golang modsecurity compatible web application firewall library. From 3.0.0 until 3.8.0, the t:jsDecode transformation in internal/transformations/js_decode.go:64-70 includes the backslash in the octal buffer, causing ParseInt to fail and return a null byte. The flaw is triggered when a rule relies on t:jsDecode and the request contains JavaScript octal escape sequences. An unauthenticated attacker can encode attack syntax with JavaScript octal escapes so the backend decodes the intended bytes while Coraza rules using t:jsDecode inspect corrupted null-byte output. The mismatch can bypass WAF rules and expose the protected application to attacks such as cross-site scripting or SQL injection. This issue is fixed in version 3.8.0.

Weakness: CWE-193 (Off-by-one Error), CWE-693 (Protection Mechanism Failure), CWE-172 (Improper Encoding or Decoding of Data)

## Which versions are affected by CVE-2026-104774?

5 open source packages ship an affected version, including github.com/corazawaf/coraza/v3, github.com/corazawaf/coraza and github.com/corazawaf/coraza/v2.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/corazawaf/coraza/v3` | Go | From 3.0.0 | 3.8.0 |
| `github.com/corazawaf/coraza/v3` | Go | From 3.0.0 | 3.8.0 |
| `github.com/corazawaf/coraza/v3` | Go | From 3.0.0 | 3.8.0 |
| `github.com/corazawaf/coraza` | Go | All versions | None |
| `github.com/corazawaf/coraza/v2` | Go | All versions | None |

## How do I fix CVE-2026-104774?

Upgrade github.com/corazawaf/coraza/v3 to 3.8.0 or later.

## Is CVE-2026-104774 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104774 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104774 and fix it if it is affected.

What it is: CVE-2026-104774 is a medium-severity vulnerability in corazawaf coraza, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104774 exists.

Affected packages and fixed versions:
- github.com/corazawaf/coraza/v3 (Go): affected from 3.0.0; fixed in 3.8.0
- github.com/corazawaf/coraza/v3 (Go): affected from 3.0.0; fixed in 3.8.0
- github.com/corazawaf/coraza/v3 (Go): affected from 3.0.0; fixed in 3.8.0
- github.com/corazawaf/coraza (Go): affected all versions; no fix listed
- github.com/corazawaf/coraza/v2 (Go): affected all versions; no fix listed

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-2026-104774/ (Markdown: https://insights.sbomify.com/CVE-2026-104774/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104774
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104774
- OSV: https://osv.dev/vulnerability/CVE-2026-104774

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104774/
Summaries are generated and may contain mistakes; the official description above is the record.