{"id":"CVE-2026-54738","state":"PUBLISHED","title":"Lemmy: Rate limit bypass via X-Forwarded-For header spoofing in actix-web ConnectionInfo","description":"Lemmy is a link aggregator and forum for the fediverse. Prior to 0.19.19 and 1.0.0-beta.1, actix-web ConnectionInfo::realip_remote_addr reads the first value of X-Forwarded-For as the client address used by raw_ip_key in crates/utils/src/rate_limit/mod.rs. Lemmy's bundled docker/nginx.conf uses $proxy_add_x_forwarded_for instead of $remote_addr, which appends the real client address to an X-Forwarded-For value supplied by the client. An unauthenticated attacker can therefore place a different spoofed address first on each request and receive a new rate-limit bucket, bypassing limits on POST /api/v4/account/auth/register, POST /api/v4/account/auth/login, POST /api/v4/post, POST /api/v4/comment, GET /api/v4/search, POST /api/v4/image, and POST /api/v4/account/import_settings. This permits excessive account creation, brute-force attempts, spam, scraping, uploads, and repeated imports. This issue is fixed in versions 0.19.19 and 1.0.0-beta.1.","publishedAt":"2026-08-19T20:27:45.162Z","updatedAt":"2026-08-21T21:48:26.962Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["LemmyNet lemmy"],"affected":[{"vendor":"LemmyNet","product":"lemmy","versions":[{"version":"< 0.19.19","status":"affected"},{"version":">= 1.0.0-alpha.5, < 1.0.0-beta.1","status":"affected"}]}],"references":["https://github.com/LemmyNet/lemmy/security/advisories/GHSA-2hrg-7x4g-9vpg","https://github.com/LemmyNet/lemmy/pull/6574","https://github.com/LemmyNet/lemmy/pull/6575","https://github.com/LemmyNet/lemmy/commit/41513c89ceecee719bff05acfe613e3b1e85f23c","https://github.com/LemmyNet/lemmy/commit/8b5b2aa78417b53ff3622c01f5bed2f1590f3b82","https://github.com/LemmyNet/lemmy/releases/tag/0.19.19","https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-beta.1","https://join-lemmy.org/news/2026-06-09_-_Lemmy_Release_v0.19.19"],"weaknesses":["CWE-799"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54738.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54738","state":"PUBLISHED","datePublished":"2026-08-19T20:27:45.162Z","dateUpdated":"2026-08-21T21:48:26.962Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-15T23:07:33.233Z"},"containers":{"cna":{"title":"Lemmy: Rate limit bypass via X-Forwarded-For header spoofing in actix-web ConnectionInfo","descriptions":[{"lang":"en","value":"Lemmy is a link aggregator and forum for the fediverse. Prior to 0.19.19 and 1.0.0-beta.1, actix-web ConnectionInfo::realip_remote_addr reads the first value of X-Forwarded-For as the client address used by raw_ip_key in crates/utils/src/rate_limit/mod.rs. Lemmy's bundled docker/nginx.conf uses $proxy_add_x_forwarded_for instead of $remote_addr, which appends the real client address to an X-Forwarded-For value supplied by the client. An unauthenticated attacker can therefore place a different spoofed address first on each request and receive a new rate-limit bucket, bypassing limits on POST /api/v4/account/auth/register, POST /api/v4/account/auth/login, POST /api/v4/post, POST /api/v4/comment, GET /api/v4/search, POST /api/v4/image, and POST /api/v4/account/import_settings. This permits excessive account creation, brute-force attempts, spam, scraping, uploads, and repeated imports. This issue is fixed in versions 0.19.19 and 1.0.0-beta.1."}],"affected":[{"vendor":"LemmyNet","product":"lemmy","versions":[{"version":"< 0.19.19","status":"affected"},{"version":">= 1.0.0-alpha.5, < 1.0.0-beta.1","status":"affected"}]}],"references":[{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-2hrg-7x4g-9vpg","name":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-2hrg-7x4g-9vpg","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/LemmyNet/lemmy/pull/6574","name":"https://github.com/LemmyNet/lemmy/pull/6574","tags":["x_refsource_MISC"]},{"url":"https://github.com/LemmyNet/lemmy/pull/6575","name":"https://github.com/LemmyNet/lemmy/pull/6575","tags":["x_refsource_MISC"]},{"url":"https://github.com/LemmyNet/lemmy/commit/41513c89ceecee719bff05acfe613e3b1e85f23c","name":"https://github.com/LemmyNet/lemmy/commit/41513c89ceecee719bff05acfe613e3b1e85f23c","tags":["x_refsource_MISC"]},{"url":"https://github.com/LemmyNet/lemmy/commit/8b5b2aa78417b53ff3622c01f5bed2f1590f3b82","name":"https://github.com/LemmyNet/lemmy/commit/8b5b2aa78417b53ff3622c01f5bed2f1590f3b82","tags":["x_refsource_MISC"]},{"url":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.19","name":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.19","tags":["x_refsource_MISC"]},{"url":"https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-beta.1","name":"https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-beta.1","tags":["x_refsource_MISC"]},{"url":"https://join-lemmy.org/news/2026-06-09_-_Lemmy_Release_v0.19.19","name":"https://join-lemmy.org/news/2026-06-09_-_Lemmy_Release_v0.19.19","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-799","lang":"en","description":"CWE-799: Improper Control of Interaction Frequency","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-19T20:27:45.162Z"},"source":{"advisory":"GHSA-2hrg-7x4g-9vpg","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-21T21:09:45.793083Z","id":"CVE-2026-54738","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-21T21:48:26.962Z"}}]}}}