CVE-2026-6103

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (5th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 4.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

phar_tar_number() parses the octal size field of a TAR header into a uint32_t with no overflow check. The field is 11 octal digits wide and holds values up to 0x1FFFFFFFF, so a size above 0xFFFFFFFF silently wraps. The parser then skips the wrong number of data blocks and interprets attacker-controlled file content as the next TAR header, which lets a crafted archive inject entries that PharData reports and extracts as if they were genuine.

CVSS v3
4.3
EG Score
4.3MEDIUMmedium confidence
EG Risk
24
EG Risk 24/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity43% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.2%
EPSS %ILE
5th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 25, 2026

Last Modified

September 29, 2026

Advisory Details (1)

Auto-updated Sep 25, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection · Advisory · php/php-src · GitHub

https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85

Vendor Advisories for CVE-2026-6103(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatphp-main-8.5.11-2.hum12026-09-23redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 20× in last 7d / 26× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-04 01:31 UTCEG score recompute
  2. 2026-10-04 01:31 UTCVendor advisory
  3. 2026-10-03 14:26 UTCEPSS rescore
  4. 2026-10-03 00:45 UTCEG score recompute
  5. 2026-10-03 00:45 UTCVendor advisory
  6. 2026-10-02 17:56 UTCEPSS rescore
  7. 2026-10-02 00:03 UTCEG score recompute
  8. 2026-10-02 00:03 UTCVendor advisory
  9. 2026-10-01 19:50 UTCEPSS rescore
  10. 2026-09-30 22:58 UTCEG score recompute
  11. 2026-09-30 22:58 UTCVendor advisory
  12. 2026-09-30 15:03 UTCEPSS rescore
  13. 2026-09-29 22:16 UTCEG score recompute
  14. 2026-09-29 22:16 UTCVendor advisory
  15. 2026-09-28 23:23 UTCEG score recompute
  16. 2026-09-28 23:23 UTCVendor advisory
  17. 2026-09-28 13:52 UTCEPSS rescore
  18. 2026-09-27 22:42 UTCEG score recompute
  19. 2026-09-27 22:42 UTCVendor advisory
  20. 2026-09-27 13:48 UTCEPSS rescore
  21. 2026-09-26 22:00 UTCEG score recompute
  22. 2026-09-26 22:00 UTCVendor advisory
  23. 2026-09-26 15:59 UTCEPSS rescore
  24. 2026-09-25 21:19 UTCEG score recompute
  25. 2026-09-25 20:24 UTCEG score recompute
Show 1 more
  1. 2026-09-25 20:24 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-6103?
CVE-2026-6103 is a medium vulnerability published on September 25, 2026. phartarnumber() parses the octal size field of a TAR header into a uint32_t with no overflow check. The field is 11 octal digits wide and holds values up to 0x1FFFFFFFF, so a size above 0xFFFFFFFF silently wraps. The parser then skips the wrong number of data blocks and interprets…
When was CVE-2026-6103 disclosed?
CVE-2026-6103 was first published on September 25, 2026, with the most recent update on September 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6103 actively exploited?
CVE-2026-6103 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (5th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-6103?
CVE-2026-6103 has a CVSS base score of 4.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-6103?
A fix for CVE-2026-6103 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-6103 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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