CVE-2023-40577 | Alertmanager UI is vulnerable to stored XSS via the /api/v1/alerts endpoint

Alertmanager handles alerts sent by client applications such as the Prometheus server. An attacker with the permission to perform POST requests on the /api/v1/alerts endpoint could be able to execute arbitrary JavaScript code on the users of Prometheus Alertmanager. This issue has been fixed in Alertmanager version 0.2.51.

Published: 2023-08-25 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-40577 is rated Moderate Risk (62.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 3.58%). EPSS rose +1.58% over the last day, indicating growing attacker interest. 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-2023-40577

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 2026-03-05 1.99% 3.58% +1.58%
2 2026-03-04 0.99% 1.99% +1.01%
3 2026-03-01 — 0.99% —

Full EPSS history (36 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-40577

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N 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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N 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:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.3 2.7 [email protected]

Weakness enumeration for CVE-2023-40577

GitHub Security Advisory for CVE-2023-40577

GHSA-v86x-5fm3-5p7j · Severity: medium · Ecosystem: go — Alertmanager UI is vulnerable to stored XSS via the /api/v1/alerts endpoint

OS Trackers for CVE-2023-40577

vendor priority summary link
alpine medium CVE-2023-40577: 1 source package rows (alertmanager); 6 state rows across 6 repos (3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 5, open 1. https://security.alpinelinux.org/vuln/CVE-2023-40577
debian unimportant CVE-2023-40577 unimportant priority: Debian including 1 source packages (prometheus-alertmanager), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2023-40577
redhat medium — https://access.redhat.com/security/cve/CVE-2023-40577
suse high — https://www.suse.com/security/cve/CVE-2023-40577/
ubuntu medium CVE-2023-40577 medium priority: Ubuntu including 1 source packages (prometheus-alertmanager), 12 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 4, not-affected 4, released 4. https://ubuntu.com/security/CVE-2023-40577

Affected software / configurations for CVE-2023-40577

Vendor Product Version Raw CPE
prometheus alertmanager 0.25.0 cpe:2.3:a:prometheus:alertmanager:0.25.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2023-40577

cvelogic Threat Intelligence