{"id":"CVE-2026-54738","aliases":["EUVD-2026-62850","GHSA-2hrg-7x4g-9vpg"],"status":"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.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00559,"percentile":0.47046,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-799"],"published":"2026-08-19T20:27:45Z","modified":"2026-10-28T02:30:38Z","products":[{"vendor":"lemmynet","product":"lemmy"}],"references":[{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-2hrg-7x4g-9vpg","tags":["x_refsource_CONFIRM","advisory"]},{"url":"https://github.com/LemmyNet/lemmy/pull/6574","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/LemmyNet/lemmy/pull/6575","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/LemmyNet/lemmy/commit/41513c89ceecee719bff05acfe613e3b1e85f23c","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/LemmyNet/lemmy/commit/8b5b2aa78417b53ff3622c01f5bed2f1590f3b82","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.19","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-beta.1","tags":["x_refsource_MISC","web"]},{"url":"https://join-lemmy.org/news/2026-06-09_-_Lemmy_Release_v0.19.19","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54738.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54738","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-54738","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.","status":"published","published":"2026-08-19T20:27:45.162Z","modified":"2026-08-21T21:48:26.962Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-799"],"updated_at":"2026-11-02T13:38:09.774038Z"}],"euvd":[{"id":"EUVD-2026-62850","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.","status":"published","published":"2026-08-19T20:27:45Z","modified":"2026-08-21T21:48:26Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T18:01:36.505605Z"}],"nvd":[{"id":"CVE-2026-54738","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.","status":"published","published":"2026-08-19T21:16:58.073Z","modified":"2026-09-09T21:15:59.613Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"secondary"}],"cwes":["CWE-799"],"updated_at":"2026-11-02T14:12:39.962615Z"}],"osv":[{"id":"CVE-2026-54738","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.","status":"published","published":"2026-08-19T20:27:45.162Z","modified":"2026-10-28T02:30:38.475785427Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"cwes":["CWE-799"],"updated_at":"2026-11-02T15:45:10.818486Z"}]}}