CVE-2026-24048 [Low] | Security Bypass in Backstage\/backend Defaults

Backstage is an open framework for building developer portals, and @backstage/backend-defaults provides the default implementations and setup for a standard Backstage backend app. Prior to versions 0.12.2, 0.13.2, 0.14.1, and 0.15.0, the `FetchUrlReader` component, used by the catalog and other plugins to fetch content from URLs, followed HTTP redirects automatically. This allowed an attacker who controls a host listed in `backend.reading.allow` to redirect requests to internal or sensitive URLs that are not on the allowlist, bypassing the URL allowlist security control. This is a Server-Side Request Forgery (SSRF) vulnerability that could allow access to internal resources, but it does not allow attackers to include additional request headers. This vulnerability is fixed in `@backstage/backend-defaults` version 0.12.2, 0.13.2, 0.14.1, and 0.15.0. Users should upgrade to this version or later. Some workarounds are available. Restrict `backend.reading.allow` to only trusted hosts that you control and that do not issue redirects, ensure allowed hosts do not have open redirect vulnerabilities, and/or use network-level controls to block access from Backstage to sensitive internal endpoints.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.03%	0.20%	+0.18%
2	2026-01-22	—	0.03%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.03%

0.20%

+0.18%

2026-01-22

—

0.03%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
3.5	3.1	LOW	`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. 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:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	1.8	1.4	[email protected]
3.7	3.1	LOW	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. 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:L) Some sensitive info could get out, but not a total data dump. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	2.2	1.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

3.5

3.1

LOW

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
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:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

1.8

1.4

[email protected]

3.7

3.1

LOW

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

2.2

1.4

[email protected]

OS Trackers for CVE-2026-24048

vendor	priority	summary	link
`redhat`	low	—	https://access.redhat.com/security/cve/CVE-2026-24048

vendor

priority

summary

link

redhat

low

—

https://access.redhat.com/security/cve/CVE-2026-24048

Affected software / configurations for CVE-2026-24048

Vendor	Product	Version	Raw CPE
linuxfoundation	backstage\/backend_defaults	< 0.12.2	cpe:2.3:a:linuxfoundation:backstage\/backend_defaults::::::node.js::*
linuxfoundation	backstage\/backend_defaults	>= 0.13.0, <= 0.13.2	cpe:2.3:a:linuxfoundation:backstage\/backend_defaults::::::node.js::*
linuxfoundation	backstage\/backend_defaults	>= 0.14.0, <= 0.14.1	cpe:2.3:a:linuxfoundation:backstage\/backend_defaults::::::node.js::*

References for CVE-2026-24048

URL	Tags
https://github.com/backstage/backstage/commit/27f9061d24affd1b9212fe0abd476bfc3fbaedcb	Patch
https://github.com/backstage/backstage/security/advisories/GHSA-q2x5-4xjx-c6p9	Vendor Advisory

URL

CVE-2026-24048 | Backstage has a Possible SSRF when reading from allowed URL's in `backend.reading.allow`

Exploit prediction scoring system (EPSS) score for CVE-2026-24048

Common vulnerability scoring system (CVSS) metrics for CVE-2026-24048

Weakness enumeration for CVE-2026-24048

GitHub Security Advisory for CVE-2026-24048

OS Trackers for CVE-2026-24048

Affected software / configurations for CVE-2026-24048

References for CVE-2026-24048