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Fencer Vulns
medium 5.3

CVE-2024-56159 json

Server source code is exposed to the public if sourcemaps are enabled

published 2024-12-19 22 mo ago modified 2026-06-17 4 mo ago also EUVD-2024-3552 , GHSA-49w6-73cw-chjr

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known, plus a Nuclei check

Summary

Astro is a web framework for content-driven websites. A bug in the build process allows any unauthenticated user to read parts of the server source code. During build, along with client assets such as css and font files, the sourcemap files **for the server code** are moved to a publicly-accessible folder. Any outside party can read them with an unauthorized HTTP GET request to the same server hosting the rest of the website. While some server files are hashed, making their access obscure, the files corresponding to the file system router (those in `src/pages`) are predictably named. For example. the sourcemap file for `src/pages/index.astro` gets named `dist/client/pages/index.astro.mjs.map`. This vulnerability is the root cause of issue #12703, which links to a simple stackblitz project demonstrating the vulnerability. Upon build, notice the contents of the `dist/client` (referred to as `config.build.client` in astro code) folder. All astro servers make the folder in question accessible to the public internet without any authentication. It contains `.map` files corresponding to the code that runs on the server. All **server-output** projects on Astro 5 versions **v5.0.3** through **v5.0.7**, that have **sourcemaps enabled**, either directly or through an add-on such as `sentry`, are affected. The fix for **server-output** projects was released in **astro@5.0.8**. Additionally, all **static-output** projects built using Astro 4 versions **4.16.17 or older**, or Astro 5 versions **5.0.8 or older**, that have **sourcemaps enabled** are also affected. The fix for **static-output** projects was released in **astro@5.0.9**, and backported to Astro v4 in **astro@4.16.18**. The immediate impact is limited to source code. Any secrets or environment variables are not exposed unless they are present verbatim in the source code. There is no immediate loss of integrity within the the vulnerable server. However, it is possible to subsequently discover another vulnerability via the revealed source code . There is no immediate impact to availability of the vulnerable server. However, the presence of an unsafe regular expression, for example, can quickly be exploited to subsequently compromise the availability. The fix for **server-output** projects was released in **astro@5.0.8**, and the fix for **static-output** projects was released in **astro@5.0.9** and backported to Astro v4 in **astro@4.16.18**. Users are advised to update immediately if they are using sourcemaps or an integration that enables sourcemaps.

Patch / fix

  • npm astro 4.16.18, 5.0.8
  • astro astro 4.16.18, 5.0.8

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
22 mo ago

Exploit prediction

1.54% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Astro - Information Disclosure nuclei detection template
  • github.com https://github.com/withastro/astro/security/advisories/GHSA-49w6-73cw-chjr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 7.8 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:H/SI:L/SA:L
CNA 4.0 7.8 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:H/SI:L/SA:L/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
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm astro
>=5.0.0-alpha.0, <5.0.8
<4.16.18
5.0.8
4.16.18

Affected products

  • withastro astro

Classification

Weakness
  • CWE-219 Storage of File with Sensitive Data Under Web Root

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.