CVE-2026-54741

5.3 MEDIUM 0.5% exploit odds Fix listed Auth & access

What it is

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.

At a glance

Exploitability: Can be exploited over the network with a low-privilege account. Limited direct impact.
Exploit odds: 0.5% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-08-19 21:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-09-09 21:15 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.5% in the next 30 days (EPSS).
Severity: 5.3 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-08-19 21:16 UTC
Last modified: 2026-09-09 21:15 UTC
Exploit probability: 0.5% · EPSS, next 30 days
Weakness: CWE-862 · Missing authorization
Record status: Deferred

Attack profile CVSS 4.0 · 5.3

Attack vector: Network
Complexity: Low
Attack requirements: None
Privileges needed: Low
User interaction: None
Confidentiality: None
Integrity: Low
Availability: None

Raw vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-54741.md and follow it. Check whether this project is affected by CVE-2026-54741. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record