isomorphic-git: Unbounded memory allocation from attacker-controlled delta target size (DoS)
CVSS score
4.3
EPSS probability
—
Risk score
0.4
Published
5 h ago
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Vulnerability description
DayBreach AI Explanation
Verified against sourcesSources read
1
Source agreement
Tam uyum
Evidence confidence
%55
Short explanation
A vulnerability in isomorphic-git allows attackers to trigger unbounded memory allocation via packfile delta target size, leading to a DoS condition.
This vulnerability can cause containers, serverless functions, and small virtual machines to terminate, resulting in service disruption.
What should be done?
- Follow vendor advisories
- Keep versions updated
- Apply relevant patches
Chain of evidence and sources
isomorphic-git, src/utils/applyDelta.js içinde sunucu kontrollü targetSize değerini Buffer.alloc(targetSize) fonksiyonuna sınırlar olmadan aktarır.
Kötü amaçlı bir uzak sunucu, git.clone veya git.fetch işlemlerinin yaklaşık 2 GB bellek tahsis etmesine neden olan delta başlıkları gönderebilir.
Show the technical text from the sources
isomorphic-git is a pure JavaScript implementation of Git for Node.js and browsers. Prior to 1.38.6, isomorphic-git reads a server-controlled targetSize while applying a packfile delta in src/utils/applyDelta.js and passes it without a bound to Buffer.alloc(targetSize). A malicious or man-in-the-middle-controlled remote can send one delta header that causes git.clone() or git.fetch() to allocate approximately 2 GB before validating the actual delta output. GitPackIndex.fromPack swallows the later size-mismatch error, so a host with sufficient memory may retain the resource waste without a visible failure, while containers, serverless functions, and small virtual machines may terminate. Node.js heap limits do not mitigate the off-heap Buffer allocation. This issue is fixed in version 1.38.6.
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
CWE: CWE-400, CWE-789
This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-63476 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | isomorphic-git | isomorphic-git | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 4.3 | CVSS V3_1 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L | CVE CNA |
| 4.3 | CVSS V31 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-63476 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-63476 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
CVSS Vector Radar Chart
4.3 / 10Vulnerability Scoring Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:LYama durumu bilinmiyor
Weakness Type (CWE & CAPEC)
Similar Vulnerabilities
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