CVE-2024-52815 | Synapse allows a a malformed invite to break the invitee's `/sync`

Synapse is an open-source Matrix homeserver. Synapse versions before 1.120.1 fail to properly validate invites received over federation. This vulnerability allows a malicious server to send a specially crafted invite that disrupts the invited user's /sync functionality. Synapse 1.120.1 rejects such invalid invites received over federation and restores the ability to sync for affected users.

Published: 2024-12-03 Last update: 2025-08-26 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-52815 is rated Moderate Risk (55.1/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.35%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2024-52815

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-23 0.25% 0.35% +0.10%
2 2026-01-11 0.09% 0.25% +0.16%
3 2025-11-21 — 0.09% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-52815

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.7 4.0 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2024-52815

GitHub Security Advisory for CVE-2024-52815

GHSA-f3r3-h2mq-hx2h · Severity: high · Ecosystem: pip — Synapse allows a a malformed invite to break the invitee's `/sync`

OS Trackers for CVE-2024-52815

vendor priority summary link
alpine — CVE-2024-52815: 1 source package rows (synapse); 40 state rows across 4 repos (3.20-community, 3.21-community, 3.22-community, edge-community); fixed 4, open 36. https://security.alpinelinux.org/vuln/CVE-2024-52815
debian not yet assigned CVE-2024-52815 not yet assigned priority: Debian including 1 source packages (matrix-synapse), 2 status rows across 2 suites (forky, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2024-52815
ubuntu medium CVE-2024-52815 medium priority: Ubuntu including 1 source packages (matrix-synapse), 6 status rows across 6 suites (bionic, focal, jammy, noble, oracular, upstream): deferred 4, ignored 1, released 1. https://ubuntu.com/security/CVE-2024-52815

Affected software / configurations for CVE-2024-52815

Vendor Product Version Raw CPE
matrix synapse < 1.120.1 cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*

References for CVE-2024-52815

cvelogic Threat Intelligence