150 lines
6.9 KiB
JSON
150 lines
6.9 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-54743",
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"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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"state": "PUBLISHED",
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"assignerShortName": "GitHub_M",
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"dateReserved": "2026-06-15T23:12:41.964Z",
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"datePublished": "2026-08-19T20:18:43.124Z",
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"dateUpdated": "2026-08-21T18:17:01.041Z"
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},
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"containers": {
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"cna": {
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"title": "Lemmy: Stored XSS via markdown image alt-text in lemmy-ui html5-embed",
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"problemTypes": [
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{
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"descriptions": [
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{
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"cweId": "CWE-79",
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"lang": "en",
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"description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
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"type": "CWE"
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}
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]
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}
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],
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"metrics": [
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{
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"cvssV4_0": {
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"attackVector": "NETWORK",
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"attackComplexity": "LOW",
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"attackRequirements": "NONE",
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"privilegesRequired": "NONE",
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"userInteraction": "PASSIVE",
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"vulnConfidentialityImpact": "NONE",
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"vulnIntegrityImpact": "NONE",
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"vulnAvailabilityImpact": "NONE",
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"subConfidentialityImpact": "HIGH",
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"subIntegrityImpact": "HIGH",
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"subAvailabilityImpact": "NONE",
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"baseScore": 6.4,
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"baseSeverity": "MEDIUM",
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"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N",
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"version": "4.0"
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}
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}
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],
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"references": [
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{
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"name": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-2g66-9fr3-ppwj",
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"tags": [
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"x_refsource_CONFIRM"
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],
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"url": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-2g66-9fr3-ppwj"
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},
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{
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"name": "https://github.com/LemmyNet/lemmy-ui/pull/4213",
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"tags": [
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"x_refsource_MISC"
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],
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"url": "https://github.com/LemmyNet/lemmy-ui/pull/4213"
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},
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{
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"name": "https://github.com/LemmyNet/lemmy-ui/commit/81a3fe07f2a5acc11188320534aa6bf937ebf7ff",
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"tags": [
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"x_refsource_MISC"
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],
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"url": "https://github.com/LemmyNet/lemmy-ui/commit/81a3fe07f2a5acc11188320534aa6bf937ebf7ff"
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},
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{
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"name": "https://github.com/LemmyNet/lemmy/releases/tag/0.19.19-beta.1",
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"tags": [
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"x_refsource_MISC"
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],
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"url": "https://github.com/LemmyNet/lemmy/releases/tag/0.19.19-beta.1"
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}
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],
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"affected": [
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{
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"vendor": "LemmyNet",
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"product": "lemmy",
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"versions": [
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{
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"version": "< 0.19.19-beta.1",
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"status": "affected"
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}
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]
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}
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],
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"providerMetadata": {
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"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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"shortName": "GitHub_M",
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"dateUpdated": "2026-08-19T20:18:43.124Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "Lemmy is a link aggregator and forum for the fediverse. Prior to lemmy-ui 0.19.19-beta.1, LemmyNet/lemmy-ui renders Markdown in src/shared/markdown.ts for post bodies, comment bodies, private messages, and community and site sidebars through mdToHtml, which returns a raw __html object that Inferno injects without a sanitizer pass. setupMarkdown configures html as false but registers markdown-it-html5-embed@1.0.0 with useImageSyntax enabled, so an image targeting video media becomes a video element whose fallback incorporates the image alt text through unescaped string replacement. The html setting does not apply to plugin-generated output, allowing crafted alt text to reach the DOM as live HTML in contexts that do not use mdToHtmlNoImages. An approved member or a remote federated instance can store such content, and a viewer who renders it may execute JavaScript in the lemmy-ui origin, exposing the viewer's session and authenticated actions. The advisory notes that Content Security Policy prevents the described exploit in production, but also states that the tested default self-hosted deployment serves no Content-Security-Policy. This issue is fixed in lemmy-ui version 0.19.19-beta.1."
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}
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],
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"source": {
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"advisory": "GHSA-2g66-9fr3-ppwj",
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"discovery": "UNKNOWN"
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}
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},
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"adp": [
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{
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"references": [
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{
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"url": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-2g66-9fr3-ppwj",
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"tags": [
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"exploit"
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]
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}
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],
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"metrics": [
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{
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"other": {
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"type": "ssvc",
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"content": {
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"timestamp": "2026-08-21T18:16:39.227018Z",
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"id": "CVE-2026-54743",
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"options": [
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{
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"Exploitation": "poc"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"role": "CISA Coordinator",
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"version": "2.0.3"
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}
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2026-08-21T18:17:01.041Z"
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}
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}
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]
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}
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} |