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CVE-2026-6103

Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection

CVSS 3.1 4.3 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

Historical advisory recorded 23 Oct 2026 15:48:27 UTC. Read the latest advisory.

cve-program · CVE-2026-6103

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-6103

Published

PHP

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "PHP Group",
                    "product": "PHP",
                    "versions": [
                        {
                            "status": "affected",
                            "version": "8.2.*",
                            "lessThan": "8.2.34",
                            "versionType": "semver"
                        },
                        {
                            "status": "affected",
                            "version": "8.3.*",
                            "lessThan": "8.3.35",
                            "versionType": "semver"
                        },
                        {
                            "status": "affected",
                            "version": "8.4.*",
                            "lessThan": "8.4.26",
                            "versionType": "semver"
                        },
                        {
                            "status": "affected",
                            "version": "8.5.*",
                            "lessThan": "8.5.11",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

Original source record · Cite this exact observation · Complete original publisher JSON