PHP up to 8.2.33/8.3.34/8.4.25/8.5.10 Tar Header Parser phar_tar_number integer overflow

Summaryinfo

A vulnerability categorized as problematic has been discovered in PHP up to 8.2.33/8.3.34/8.4.25/8.5.10. The affected element is the function phar_tar_number of the component Tar Header Parser. The manipulation results in integer overflow. This vulnerability is known as CVE-2026-6103. Attacking locally is a requirement. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in PHP up to 8.2.33/8.3.34/8.4.25/8.5.10. It has been classified as problematic. Affected is the function phar_tar_number of the component Tar Header Parser. The manipulation with an unknown input leads to a integer overflow vulnerability. CWE is classifying the issue as CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. This is going to have an impact on integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-6103 since 04/11/2026. The exploitability is told to be easy. The attack needs to be approached locally. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/25/2026).

Upgrading to version 8.2.34, 8.3.35, 8.4.26 or 8.5.11 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Programming Language Software

Name

• PHP

Version

• 8.2.0
• 8.2.1
• 8.2.2
• 8.2.3
• 8.2.4
• 8.2.5
• 8.2.6
• 8.2.7
• 8.2.8
• 8.2.9
• 8.2.10
• 8.2.11
• 8.2.12
• 8.2.13
• 8.2.14
• 8.2.15
• 8.2.16
• 8.2.17
• 8.2.18
• 8.2.19
• 8.2.20
• 8.2.21
• 8.2.22
• 8.2.23
• 8.2.24
• 8.2.25
• 8.2.26
• 8.2.27
• 8.2.28
• 8.2.29
• 8.2.30
• 8.2.31
• 8.2.32
• 8.2.33
• 8.3.0
• 8.3.1
• 8.3.2
• 8.3.3
• 8.3.4
• 8.3.5
• 8.3.6
• 8.3.7
• 8.3.8
• 8.3.9
• 8.3.10
• 8.3.11
• 8.3.12
• 8.3.13
• 8.3.14
• 8.3.15
• 8.3.16
• 8.3.17
• 8.3.18
• 8.3.19
• 8.3.20
• 8.3.21
• 8.3.22
• 8.3.23
• 8.3.24
• 8.3.25
• 8.3.26
• 8.3.27
• 8.3.28
• 8.3.29
• 8.3.30
• 8.3.31
• 8.3.32
• 8.3.33
• 8.3.34
• 8.4.0
• 8.4.1
• 8.4.2
• 8.4.3
• 8.4.4
• 8.4.5
• 8.4.6
• 8.4.7
• 8.4.8
• 8.4.9
• 8.4.10
• 8.4.11
• 8.4.12
• 8.4.13
• 8.4.14
• 8.4.15
• 8.4.16
• 8.4.17
• 8.4.18
• 8.4.19
• 8.4.20
• 8.4.21
• 8.4.22
• 8.4.23
• 8.4.24
• 8.4.25
• 8.5.0
• 8.5.1
• 8.5.2
• 8.5.3
• 8.5.4
• 8.5.5
• 8.5.6
• 8.5.7
• 8.5.8
• 8.5.9
• 8.5.10

License

• open-source

Website

• Product: https://www.php.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

Discussion