Tarfile infinite loop during parsing with negative member offset
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.6%
exploitation probability
0.6%top 51% of all CVEs
observed exploitation
nono source reports it
There is a defect in the CPython “tarfile” module affecting the “TarFile” extraction and entry enumeration APIs. The tar implementation would process tar archives with negative offsets without error, resulting in an infinite loop and deadlock during the parsing of maliciously crafted tar archives.
This vulnerability can be mitigated by including the following patch after importing the “tarfile” module: https://gist.github.com/sethmlarson/1716ac5b82b73dbcbf23ad2eff8b33e1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
Python Software Foundation · CPythonReferences
https://gist.github.com/sethmlarson/1716ac5b82b73dbcbf23ad2eff8b33e1https://github.com/python/cpython/commit/57f5981d6260ed21266e0c26951b8564cc252bc2https://github.com/python/cpython/commit/7040aa54f14676938970e10c5f74ea93cd56aa38https://github.com/python/cpython/commit/73f03e4808206f71eb6b92c579505a220942ef19https://github.com/python/cpython/commit/b4ec17488eedec36d3c05fec127df71c0071f6cbhttps://github.com/python/cpython/commit/c9d9f78feb1467e73fd29356c040bde1c104f29fhttps://github.com/python/cpython/commit/cdae923ffe187d6ef916c0f665a31249619193fehttps://github.com/python/cpython/commit/fbc2a0ca9ac8aff6887f8ddf79b87b4510277227https://github.com/python/cpython/issues/130577https://github.com/python/cpython/pull/137027https://mail.python.org/archives/list/security-announce@python.org/thread/ZULLF3IZ726XP5EY7XJ7YIN3K5MDYR2D/http://www.openwall.com/lists/oss-security/2025/07/28/1