{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2025-21922", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-21922", "idYear": 2025, "status": "PUBLISHED", "publishedAt": "2025-04-01T15:40:55.711Z", "updatedAt": "2026-05-11T21:09:07.881Z", "importedAt": "2026-10-24T01:57:29.455Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "ppp: Fix KMSAN uninit-value warning with bpf", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nppp: Fix KMSAN uninit-value warning with bpf\n\nSyzbot caught an \"KMSAN: uninit-value\" warning [1], which is caused by the\nppp driver not initializing a 2-byte header when using socket filter.\n\nThe following code can generate a PPP filter BPF program:\n'''\nstruct bpf_program fp;\npcap_t *handle;\nhandle = pcap_open_dead(DLT_PPP_PPPD, 65535);\npcap_compile(handle, &fp, \"ip and outbound\", 0, 0);\nbpf_dump(&fp, 1);\n'''\nIts output is:\n'''\n(000) ldh [2]\n(001) jeq #0x21 jt 2 jf 5\n(002) ldb [0]\n(003) jeq #0x1 jt 4 jf 5\n(004) ret #65535\n(005) ret #0\n'''\nWen can find similar code at the following link:\nhttps://github.com/ppp-project/ppp/blob/master/pppd/options.c#L1680\nThe maintainer of this code repository is also the original maintainer\nof the ppp driver.\n\nAs you can see the BPF program skips 2 bytes of data and then reads the\n'Protocol' field to determine if it's an IP packet. Then it read the first\nbyte of the first 2 bytes to determine the direction.\n\nThe issue is that only the first byte indicating direction is initialized\nin current ppp driver code while the second byte is not initialized.\n\nFor normal BPF programs generated by libpcap, uninitialized data won't be\nused, so it's not a problem. However, for carefully crafted BPF programs,\nsuch as those generated by syzkaller [2], which start reading from offset\n0, the uninitialized data will be used and caught by KMSAN.\n\n[1] https://syzkaller.appspot.com/bug?extid=853242d9c9917165d791\n[2] https://syzkaller.appspot.com/text?tag=ReproC&x=11994913980000", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "d685096c8129c9a92689975193e268945fd21dbf" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "2f591cb158807bdcf424f66f1fbfa6e4e50f3757" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "4e2191b0fd0c064d37b0db67396216f2d4787e0f" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "3de809a768464528762757e433cd50de35bcb3c1" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "1eacd47636a9de5bee25d9d5962dc538a82d9f0b" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "8aa8a40c766b3945b40565a70349d5581458ff63" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "c036f5f2680cbdabdbbace86baee3c83721634d6" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "4c2d14c40a68678d885eab4008a0129646805bae" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.12" }, { "version": "5.4.291", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.235", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.179", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.131", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.83", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.19", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.13.7", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.13.*" }, { "version": "6.14", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }