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CVE-2026-74485

HIGHCVSS 7.1/10EPSS 0.13%

Last modified

CVE-2026-74485 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: binfmt_misc: reject a flag character as the field delimiter The registration string starts with a user chosen delimiter that separates the individual fields. So that the field parsers terminate even on a truncated string create_entry() pads the buffer with that same delimiter: memset(buf + count, del, 8); Most fields are scanned for the delimiter with strchr()/scanarg() and happily stop on the padding. EPSS estimates a 0.13% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: binfmt_misc: reject a flag character as the field delimiter The registration string starts with a user chosen delimiter that separates the individual fields. So that the field parsers terminate even on a truncated string create_entry() pads the buffer with that same delimiter: memset(buf + count, del, 8); Most fields are scanned for the delimiter with strchr()/scanarg() and happily stop on the padding. The flags field is different: instead of scanning for the delimiter check_special_flags() consumes the flag characters 'P', 'O', 'C' and 'F' and stops at the first byte that is none of them, relying on the trailing delimiter to end the scan. If the delimiter is itself a flag character the padding no longer acts as a terminator. The scan swallows all eight padding bytes and keeps reading past the end of the allocation until it hits a byte that is not a flag character. For example registering PaPEPPxPPiP with 'P' as the delimiter (name "a", type extension, magic "x", interpreter "i", empty flags) leaves the flag scan running off the end of the buffer. The registration is rejected in the end because the parser does not stop exactly at buf + count, but only after the out of bounds read has already happened. With an unlucky allocation layout the scan can walk into an unmapped page; under KASAN it is reported as a slab out of bounds read. binfmt_misc mounts are available to unprivileged users in a user namespace so the read is reachable without privileges. Reject a delimiter that is one of the flag characters up front. Such a registration was always rejected anyway, only after the out of bounds read, so no valid registration string changes meaning.

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS Probability
0.13%

2.6th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 96bd5d4fea2970b9b08265293ca7a10b9b27c0fd; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 9970e094e5d60f0d66914bf9a97d1ef19107ebf5; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < b29e3c1f375c1296362d219ff38bceddf2d2a88a; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 1819f82dee766c58295ecaacdac02cdf6837d7a4; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 1853e95c9bfe69ef1dd862b3f551e68f4a1b76cc; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 840bb9c49c3e75fb32b593d67ab32f6b77122262; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 9a2d87db3898b5993b64fd258d0334e0eba9ee0d; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 8e85d50ba1117fd446bf9a250bd8a97d48384bdc
LinuxLinux2.6.12

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-74485?
In the Linux kernel, the following vulnerability has been resolved: binfmt_misc: reject a flag character as the field delimiter The registration string starts with a user chosen delimiter that separates the individual fields. So that the field parsers terminate even on a truncated string create_entry() pads the buffer with that same delimiter: memset(buf + count, del, 8); Most fields are scanned for the delimiter with strchr()/scanarg() and happily stop on the padding. The flags field is different: instead of scanning for the delimiter check_special_flags() consumes the flag characters 'P', 'O', 'C' and 'F' and stops at the first byte that is none of them, relying on the trailing delimiter to end the scan. If the delimiter is itself a flag character the padding no longer acts as a terminator. The scan swallows all eight padding bytes and keeps reading past the end of the allocation until it hits a byte that is not a flag character. For example registering PaPEPPxPPiP with 'P' as the delimiter (name "a", type extension, magic "x", interpreter "i", empty flags) leaves the flag scan running off the end of the buffer. The registration is rejected in the end because the parser does not stop exactly at buf + count, but only after the out of bounds read has already happened. With an unlucky allocation layout the scan can walk into an unmapped page; under KASAN it is reported as a slab out of bounds read. binfmt_misc mounts are available to unprivileged users in a user namespace so the read is reachable without privileges. Reject a delimiter that is one of the flag characters up front. Such a registration was always rejected anyway, only after the out of bounds read, so no valid registration string changes meaning.
How severe is CVE-2026-74485?
CVE-2026-74485 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.
How do I fix CVE-2026-74485?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST