CVE-2026-12644 json
ts-deepmerge: Prototype Method Override leads to DoS
published 4mo ago modified 4mo ago also EUVD-2026-37991 , GHSA-87mf-gv2c-c62c
- cvss
- 5.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 43%
- public exploits
- 0
- none known
Summary
Versions of the package ts-deepmerge before 8.0.0 are vulnerable to Uncaught Exception due to the improper handling of built-in Object.prototype methods (such as toString, valueOf). When user-controlled input contains these keys with non-function values, the resulting merged object becomes broken — any string context operation throws a TypeError, crashing the application.
Patch / fix
Is CVE-2026-12644 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 4mo ago
Exploit prediction
0.51% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- gist.github.com https://gist.github.com/igorg1312/775fa00114c4d47df6ae0551779ab407 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.9 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P |
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P |
| GitHub | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
| CNA | 4.0 | 5.5 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/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 |
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | ts-deepmerge | <8.0.0 |
8.0.0 |
Affected products
- n/a ts-deepmerge
Classification
- Weakness
-
- CWE-248 Uncaught Exception
References
-
github.com
/voodoocreation/ts-deepmerge/commit/305a05831a462fb2c353d3cbbff55a0733286f8c
web
-
gist.github.com
/igorg1312/775fa00114c4d47df6ae0551779ab407
exploit, web
-
security.snyk.io
/vuln/SNYK-JS-TSDEEPMERGE-17339141
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-12644
advisory
-
github.com
/voodoocreation/ts-deepmerge
package
Sources
- CVE List CVE-2026-12644
- GitHub Advisory GHSA-87mf-gv2c-c62c
- NVD CVE-2026-12644
Fencer Intel 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.