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Fencer Intel
medium 5.8

CVE-2026-104774 json

OWASP Coraza WAF: jsDecode Off-by-One in Octal Escape Handling Enables WAF Bypass

published last mo. modified 21d ago also EUVD-2026-97825 , GHSA-pc5q-qfxp-ggqv , GO-2026-6696

cvss
5.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/corazawaf/coraza/v3 3.8.0
  • coraza coraza 3.8.0

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
27d ago

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/corazawaf/coraza/security/advisories/GHSA-pc5q-qfxp-ggqv referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
GitHub 3.1 5.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/corazawaf/coraza/v3
>=3.0.0, <3.8.0
3.8.0
go github.com/corazawaf/coraza
all versions
 no fix listed
go github.com/corazawaf/coraza/v2
all versions
 no fix listed

Affected products

  • corazawaf coraza

Classification

Weakness
  • CWE-172 Improper Encoding or Decoding of Data
  • CWE-193 Off-by-one Error
  • CWE-693 Protection Mechanism Failure

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.