CVE-2026-53366

NameCVE-2026-53366
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ipv4: account for fraggap on the paged allocation path In __ip_append_data(), when the paged-allocation branch is taken, alloclen and pagedlen are computed as alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen; datalen already includes fraggap, but the fraggap bytes carried over from the previous skb are copied into the new skb's linear area at offset transhdrlen by the subsequent skb_copy_and_csum_bits(). The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount. The non-paged branch sets alloclen to fraglen, which already accounts for fraggap because datalen does. Bring the paged branch in line by adding fraggap to alloclen and subtracting it from pagedlen. After this adjustment, copy no longer collapses to -fraggap on the paged path, so remove the stale comment describing that old arithmetic.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-4688-1, DLA-4700-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bullseye5.10.223-1fixed
bullseye (security)5.10.262-1fixed
bookworm6.1.176-1vulnerable
bookworm (security)6.1.180-1fixed
trixie6.12.94-1vulnerable
trixie (security)6.12.101-1fixed
forky7.1.3-1fixed
sid7.1.6-1fixed
linux-6.1 (PTS)bullseye (security)6.1.180-1~deb11u1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebullseye(not affected)
linuxsourcebookworm6.1.177-1DLA-4688-1
linuxsourcetrixie6.12.95-1
linuxsource(unstable)7.1.3-1
linux-6.1sourcebullseye6.1.177-1~deb11u1DLA-4700-1

Notes

[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/eca856950f7cb1a221e02b99d758409f2c5cec42 (7.2-rc1)
https://www.openwall.com/lists/oss-security/2026/07/20/2
https://blog.qwerty.or.kr/en/posts/cdf3008a-c1a4-4eca-a373-aa3a2bcf1489/

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