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Medium, CVSS 4.0amended

Coraza has Cookie Parser Confusion

CVE-2026-107835GHSA-g4qm-m288-5cp9

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/corazawaf/coraza/v3

    Affected
    < 3.8.1
    Fixed in
    3.8.1

  • Go github.com/corazawaf/coraza

    Affected
    every version
    Fixed in
    no fixed version recorded

  • Go github.com/corazawaf/coraza/v2

    Affected
    every version
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
4.0 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
EPSS
  • CVE-2026-107835: 0.30% estimated exploitation activity in the next 30 days; percentile 22.60 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Coraza's cookie parser (internal/cookies.ParseCookies) does not strip ASCII control characters (CTLs) from the edges of a cookie name/value before they're matched against REQUESTCOOKIES / REQUESTCOOKIESNAMES. When a CTL sits directly next to the = separator, Coraza absorbs it into the adjacent name or value, while several backend cookie parsers trim it away — so the WAF and the application disagree about the cookie it just received. Root cause - ParseCookies (internal/cookies/cookies.go:17,26,31) trims via net/textproto.TrimString, which strips only space (0x20) and tab (0x09). - RFC 6265 §4.1.1 defines cookie name as an HTTP token and value as cookie-octet, both excluding the full C0 control range (0x00–0x1F, 0x7F) — not just space/tab. - Input a\v=\t' (vertical tab \v next to =) keeps \v in the name (a\v), yielding name=a\v, value=\t'. Confirmed divergence from real backends | Implementation | Name | Value | |---|---|---| | Coraza (< 3.8.0) | a\v | \t' | | Python…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-g4qm-m288-5cp9

  2. Revision 2 · amended ·

    Amended from osv record GO-2026-6694

  3. Revision 1 · created ·

    Published from osv record GHSA-g4qm-m288-5cp9

Agent brief

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# Patch Next advisory brief: CVE-2026-107835

Advisory: Coraza has Cookie Parser Confusion
IDs: CVE-2026-107835, GHSA-g4qm-m288-5cp9
Record: https://patchnext.com/advisories/cve-2026-107835 (revision 3, source checked 26 Oct 2026, 15:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/corazawaf/coraza/v3 3.8.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/corazawaf/coraza/v3: affected < 3.8.1; fixed in 3.8.1
- Go github.com/corazawaf/coraza: affected every version
- Go github.com/corazawaf/coraza/v2: affected every version

## Suggested inspection (read-only)
- Go github.com/corazawaf/coraza/v3: check the installed version with your package manager.
- Go github.com/corazawaf/coraza: check the installed version with your package manager.
- Go github.com/corazawaf/coraza/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/corazawaf/coraza/v3, github.com/corazawaf/coraza, github.com/corazawaf/coraza/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6694 (OSV record GO-2026-6694 lists affected ranges: Go github.com/corazawaf/coraza >=0; Go github.com/corazawaf/coraza/v2 >=0; Go github.com/corazawaf/coraza/v3 >=0 <3.8.1 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-g4qm-m288-5cp9 (OSV record GHSA-g4qm-m288-5cp9 lists affected ranges: Go github.com/corazawaf/coraza/v3 >=0 <3.8.1 (fixed))
- Verified: https://github.com/advisories/GHSA-g4qm-m288-5cp9 (GitHub-reviewed advisory GHSA-g4qm-m288-5cp9 lists affected ranges: Go github.com/corazawaf/coraza/v3 >=0 <3.8.1)

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