Medium
Postiz: TOCTOU DNS rebinding bypasses all SSRF URL validation paths
Type: advisorySources: OSV
Postiz is an AI social media scheduling tool. From version 2.16.6 to before version 2.21.7, all SSRF protections added in v2.21.4–v2.21.6 share a fundamental TOCTOU (Time-of-Check-Time-of-Use) vulnerability: isSafePublicHttpsUrl() resolves DNS to validate the target IP, but subsequent fetch() calls resolve DNS independently. An attacker controlling a DNS server can exploit this gap via DNS rebinding to redirect requests to internal network addresses. This issue has been patched in version 2.21.7.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-42346
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 05:17 UTC · Revision 1
Source evidence
Postiz: TOCTOU DNS rebinding bypasses all SSRF URL validation paths
core-osv · Original sourcePublished 8 May 2026, 22:26 UTC
Postiz is an AI social media scheduling tool. From version 2.16.6 to before version 2.21.7, all SSRF protections added in v2.21.4–v2.21.6 share a fundamental TOCTOU (Time-of-Check-Time-of-Use) vulnerability: isSafePublicHttpsUrl() resolves DNS to validate the target IP, but subsequent fetch() calls resolve DNS independently. An attacker controlling a DNS server can exploit this gap via DNS rebinding to redirect requests to internal network addresses. This issue has been patched in version 2.21.7.
osv:CVE-2026-42346
Complete source record
{
"id": "46ae20e86c5cdd687df33baac2606888d03ee54119bc1290ebd2aeb300ac543f",
"url": "https://osv.dev/vulnerability/CVE-2026-42346",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Postiz: TOCTOU DNS rebinding bypasses all SSRF URL validation paths",
"summary": "Postiz is an AI social media scheduling tool. From version 2.16.6 to before version 2.21.7, all SSRF protections added in v2.21.4–v2.21.6 share a fundamental TOCTOU (Time-of-Check-Time-of-Use) vulnerability: isSafePublicHttpsUrl() resolves DNS to validate the target IP, but subsequent fetch() calls resolve DNS independently. An attacker controlling a DNS server can exploit this gap via DNS rebinding to redirect requests to internal network addresses. This issue has been patched in version 2.21.7.",
"evidence": "osv:CVE-2026-42346",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-42346",
"aliases": [
"CVE-2026-42346",
"GHSA-f7jj-p389-4w45"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/gitroomhq/postiz-app",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "7236213ea4520bd67b45688c2787d1f4586b3b51"
},
{
"fixed": "071143dcb01cdeb9d5d7019892f4c6ff7b19dbeb"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
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{
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"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
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],
"source": "REFERENCES_COMMIT"
},
{
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"source": "REFERENCES_TAG",
"original_tag": "v2.21.7"
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"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42346.json"
}
}
],
"modified": "2026-10-28T02:30:33.128479696Z",
"provider": "osv",
"references": [
"https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.7",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42346.json",
"https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-f7jj-p389-4w45",
"https://nvd.nist.gov/vuln/detail/CVE-2026-42346",
"https://github.com/gitroomhq/postiz-app/commit/071143dcb01cdeb9d5d7019892f4c6ff7b19dbeb"
],
"provider_metadata": {
"cwe_ids": [
"CWE-918"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42346.json"
}
},
"related_cves": [
{
"value": "CVE-2026-42346",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 500472,
"published_at": "2026-05-08T22:26:50.501+00:00"
}