Answer in brief
CVE-2026-53218 records a Medium severity (CVSS 5.5) vulnerability in netfilter: nft_exthdr: fix register tracking for F_PRESENT flag. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6 || >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <19748967d59c31d24d21d40b728570788310b237 || >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <46fc15a044e9938e7ea77786fb37edd2cd74f031 || >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <cd513e43b4b2bd1de39e2367bc4261c699a8652f || >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <67b27434c43b68a97becda98c9f0c8cf6cba2134 || >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <78069a6d8bc86c9e036eb82c2af4a19cc1871a53 || >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265 || >=c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783 <772cecf198da732faebb5dcfc46d66a505be8495 | 8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6, 19748967d59c31d24d21d40b728570788310b237, 46fc15a044e9938e7ea77786fb37edd2cd74f031, cd513e43b4b2bd1de39e2367bc4261c699a8652f, 67b27434c43b68a97becda98c9f0c8cf6cba2134, 78069a6d8bc86c9e036eb82c2af4a19cc1871a53, f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265, 772cecf198da732faebb5dcfc46d66a505be8495 |
| Linux/Linuxgeneric | 4.11 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
Published upstream
Jun 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 25, 2026
In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag nft_exthdr_init() passes user-controlled priv->len to nft_parse_register_store(), which marks that many bytes in the register bitmap as initialized. However, when NFT_EXTHDR_F_PRESENT is set, the eval paths write only 1 byte (nft_reg_store8) or 4 bytes (*dest = 0 on TCP/DCCP error path). When len > 4, registers beyond the first are never written, retaining uninitialized stack data from nft_regs. Bail out if userspace requests too much data when F_PRESENT is set.
Quoted source text, attributed separately from HOL analysis.