Lemmy is a link aggregator and forum for the fediverse. Prior to 0.19.19 and 1.0.0-alpha.18, Lemmy blocks new private messages from a sender after the recipient blocks that sender, but the edit path skips the same block check. createprivatemessage checks the recipient's block list with PersonActions::readblock before inserting a message, while editprivatemessage in crates/api/apicrud/src/privatemessage/update.rs only checks that the caller is origprivatemessage.creatorid. The update then writes new content and returns the modified PrivateMessageView without consulting the recipient's block list, allowing a blocked sender to keep changing an old message that the recipient can still see and providing a post-block harassment path. This issue is fixed in versions 0.19.19 and 1.0.0-alpha.18.
{
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54741.json",
"cwe_ids": [
"CWE-862"
],
"cna_assigner": "GitHub_M"
}{
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "0.19.19"
},
{
"introduced": "1.0.0-alpha.0"
},
{
"fixed": "1.0.0-alpha.18"
}
],
"source": [
"AFFECTED_FIELD",
"REFERENCES"
]
}