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Untriaged
Permalink CVE-2026-54741
5.3 MEDIUM
  • CVSS version (CVSS): 4.0
  • Attack Vector (AV): Network (N)
  • Attack Complexity (AC): Low (L)
  • Attack Requirement (AT): None (N)
  • Privileges Required (PR): Low (L)
  • User Interaction (UI): None (N)
  • Vulnerable System Impact Confidentiality (VC): None (N)
  • Vulnerable System Impact Integrity (VI): Low (L)
  • Vulnerable System Impact Availability (VA): None (N)
  • Subsequent System Impact Confidentiality (SC): None (N)
  • Subsequent System Impact Integrity (SI): None (N)
  • Subsequent System Impact Availability (SA): None (N)
  • Modified Attack Vector (MAV): Network (N)
  • Modified Attack Complexity (MAC): Low (L)
  • Modified Attack Requirement (MAT): None (N)
  • Modified Privileges Required (MPR): Low (L)
  • Modified User Interaction (MUI): None (N)
  • Modified Vulnerable System Impact Confidentiality (MVC): None (N)
  • Modified Vulnerable System Impact Integrity (MVI): Low (L)
  • Modified Vulnerable System Impact Availability (MVA): None (N)
  • Modified Subsequent System Impact Confidentiality (MSC): Negligible (N)
  • Modified Subsequent System Impact Integrity (MSI): Negligible (N)
  • Modified Subsequent System Impact Availability (MSA): Negligible (N)
  • Safety (S): Not Defined (X)
  • Automatable (AU): Not Defined (X)
  • Recovery (R): Not Defined (X)
  • Value Density (V): Not Defined (X)
  • Vulnerability Response Effort (RE): Not Defined (X)
  • Provider Urgency (U): Not Defined (X)
  • Confidentiality Req. (CR): Not Defined (X)
  • Integrity Req. (IR): Not Defined (X)
  • Availability Req. (AR): Not Defined (X)
  • Exploit Maturity (E): Not Defined (X)
created 1 month ago Activity log
  • Created suggestion
Lemmy: Blocked users can edit private messages sent before the block

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. create_private_message checks the recipient's block list with PersonActions::read_block before inserting a message, while edit_private_message in crates/api/api_crud/src/private_message/update.rs only checks that the caller is orig_private_message.creator_id. 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.

Affected products

lemmy
  • ==>= 1.0.0-alpha.0, < 1.0.0-alpha.18
  • ==< 0.19.19

Matching in nixpkgs

pkgs.lemmy-ui

Web frontend for a federated link aggregator

  • nixos-unstable -
  • nixos-26.05 -

pkgs.lemmy-help

CLI for generating vim help docs from emmylua comments

  • nixos-unstable -
  • nixos-26.05 -

pkgs.lemmy-server

Federated link aggregator and forum

  • nixos-unstable -
  • nixos-26.05 -

Package maintainers