How severe is CVE-2023-42450?

CVE-2023-42450 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2023-42450 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-42450?

CVE-2023-42450 primarily affects Joinmastodon Mastodon. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-42450?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-42450 published?

CVE-2023-42450 was published on 2023-09-19 and last updated on 2026-06-17.

CVE-2023-42450

CVE-2023-42450 is a medium-severity vulnerability in Joinmastodon Mastodon with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-113.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-113
Affected product: Joinmastodon Mastodon
Published: 2023-09-19
Last modified: 2026-06-17

Description

Mastodon is a free, open-source social network server based on ActivityPub. Starting in version 4.2.0-beta1 and prior to version 4.2.0-rc2, by crafting specific input, attackers can inject arbitrary data into HTTP requests issued by Mastodon. This can be used to perform confused deputy attacks if the server configuration includes `ALLOWED_PRIVATE_ADDRESSES` to allow access to local exploitable services. Version 4.2.0-rc2 has a patch for the issue.

Frequently asked questions

What is CVE-2023-42450?: Mastodon is a free, open-source social network server based on ActivityPub. Starting in version 4.2.0-beta1 and prior to version 4.2.0-rc2, by crafting specific input, attackers can inject arbitrary data into HTTP requests issued by Mastodon. This can be used to perform confused deputy attacks if the server configuration includes `ALLOWED_PRIVATE_ADDRESSES` to allow access to local exploitable services. Version 4.2.0-rc2 has a patch for the issue.
How severe is CVE-2023-42450?: CVE-2023-42450 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2023-42450 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-42450?: CVE-2023-42450 primarily affects Joinmastodon Mastodon. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-42450?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-42450 published?: CVE-2023-42450 was published on 2023-09-19 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:joinmastodon:mastodon:4.2.0:beta1:*:*:*:*:*:*
cpe:2.3:a:joinmastodon:mastodon:4.2.0:beta2:*:*:*:*:*:*
cpe:2.3:a:joinmastodon:mastodon:4.2.0:beta3:*:*:*:*:*:*
cpe:2.3:a:joinmastodon:mastodon:4.2.0:rc1:*:*:*:*:*:*

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CVE-2023-36460 — Critical (CVSS 9.9): Mastodon is a free, open-source social network server based on ActivityPub. Starting in version 3.5.0 and prior to…
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CVE-2023-36459 — Critical (CVSS 9.3): Mastodon is a free, open-source social network server based on ActivityPub. Starting in version 1.3 and prior to…

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