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VulnerabilityPublished

CVE-2026-6103: PHP · Integer Overflow or Wraparound

Affects PHPSource CVE Database V5

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Not known to be exploited · CVSS 4.3 Medium · fixed in 8.5.11 : update PHP when convenient.

Data as of 8 Nov 2026, 23:24 UTC

CVSS 3.1 base score
4.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 8.5.11, 8.4.26, 8.3.35 +1
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.

What to do

Upgrade PHP to 8.5.11, 8.4.26, 8.3.35 or 8.2.34.

Affected software

ProductAffectedFixed in
PHP GroupPHPAffected
  • ≥ 8.5.*, < 8.5.11
Fixed in
  • 8.5.11
PHP GroupPHPAffected
  • ≥ 8.4.*, < 8.4.26
Fixed in
  • 8.4.26
PHP GroupPHPAffected
  • ≥ 8.3.*, < 8.3.35
Fixed in
  • 8.3.35
PHP GroupPHPAffected
  • ≥ 8.2.*, < 8.2.34
Fixed in
  • 8.2.34

AI-suggested

If you cannot patch yet, avoid processing untrusted Phar archives or use alternative archive handling methods that do not rely on the vulnerable parsing function.

Description

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.

References

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