CVE-2026-54741 (GCVE-0-2026-54741)
Vulnerability from cvelistv5 – Published: 2026-08-19 20:13 – Updated: 2026-08-20 13:21
VLAI
EPSS
VEX
Title
Lemmy: Blocked users can edit private messages sent before the block
Summary
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.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-20 13:21 UTC
CWE
- CWE-862 - Missing Authorization
Assigner
References
7 references
| URL | Tags |
|---|---|
| https://github.com/LemmyNet/lemmy/security/adviso… | x_refsource_CONFIRM |
| https://github.com/LemmyNet/lemmy/pull/6472 | x_refsource_MISC |
| https://github.com/LemmyNet/lemmy/pull/6476 | x_refsource_MISC |
| https://github.com/LemmyNet/lemmy/commit/051b317c… | x_refsource_MISC |
| https://github.com/LemmyNet/lemmy/commit/2d169d63… | x_refsource_MISC |
| https://github.com/LemmyNet/lemmy/releases/tag/0.19.19 | x_refsource_MISC |
| https://github.com/LemmyNet/lemmy/releases/tag/1.… | x_refsource_MISC |
Impacted products
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}
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{
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"tags": [
"x_refsource_MISC"
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"url": "https://github.com/LemmyNet/lemmy/commit/051b317c9d14b91972bb372c67f319d6900beb93"
},
{
"name": "https://github.com/LemmyNet/lemmy/commit/2d169d630b86b9351e4b1dca451214b741f46150",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/LemmyNet/lemmy/commit/2d169d630b86b9351e4b1dca451214b741f46150"
},
{
"name": "https://github.com/LemmyNet/lemmy/releases/tag/0.19.19",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/LemmyNet/lemmy/releases/tag/0.19.19"
},
{
"name": "https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-alpha.18",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-alpha.18"
}
],
"source": {
"advisory": "GHSA-46g9-847m-qf8r",
"discovery": "UNKNOWN"
},
"title": "Lemmy: Blocked users can edit private messages sent before the block"
}
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"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-54741",
"datePublished": "2026-08-19T20:13:05.201Z",
"dateReserved": "2026-06-15T23:12:41.964Z",
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"epss": "0.00484",
"percentile": "0.3945"
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"version": "\u003c 0.19.19"
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{
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"lastModified": "2026-09-09T21:15:59.613",
"metrics": {
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"modifiedSubAvailabilityImpact": "NOT_DEFINED",
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"vulnConfidentialityImpact": "NONE",
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"vulnerabilityResponseEffort": "NOT_DEFINED"
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"vulnrichment": {
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"vendor": "LemmyNet",
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}
],
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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