Answer in brief
CVE-2025-21758 records a Medium severity (CVSS 5.5) vulnerability in ipv6: mcast: add RCU protection to mld_newpack(). 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 1518-4 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.
Answer in brief
CVE-2025-21758 records a Medium severity (CVSS 5.5) vulnerability in ipv6: mcast: add RCU protection to mld_newpack(). 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 1518-4 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 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <29fa42197f26a97cde29fa8c40beddf44ea5c8f3 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <e8af3632a7f2da83e27b083f787bced1faba00b1 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <1b91c597b0214b1b462eb627ec02658c944623f2 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <25195f9d5ffcc8079ad743a50c0409dbdc48d98a || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <d60d493b0e65647e0335e6a7c4547abcea7df8e9 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <a527750d877fd334de87eef81f1cb5f0f0ca3373 | 29fa42197f26a97cde29fa8c40beddf44ea5c8f3, e8af3632a7f2da83e27b083f787bced1faba00b1, 1b91c597b0214b1b462eb627ec02658c944623f2, 25195f9d5ffcc8079ad743a50c0409dbdc48d98a, d60d493b0e65647e0335e6a7c4547abcea7df8e9, a527750d877fd334de87eef81f1cb5f0f0ca3373 |
| Linux/Linuxgeneric | 2.6.26 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
Published upstream
Feb 27, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 14, 2026
In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: add RCU protection to mld_newpack() mld_newpack() can be called without RTNL or RCU being held. Note that we no longer can use sock_alloc_send_skb() because ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep. Instead use alloc_skb() and charge the net->ipv6.igmp_sk socket under RCU protection.
Quoted source text, attributed separately from HOL analysis.
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 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <29fa42197f26a97cde29fa8c40beddf44ea5c8f3 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <e8af3632a7f2da83e27b083f787bced1faba00b1 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <1b91c597b0214b1b462eb627ec02658c944623f2 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <25195f9d5ffcc8079ad743a50c0409dbdc48d98a || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <d60d493b0e65647e0335e6a7c4547abcea7df8e9 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <a527750d877fd334de87eef81f1cb5f0f0ca3373 | 29fa42197f26a97cde29fa8c40beddf44ea5c8f3, e8af3632a7f2da83e27b083f787bced1faba00b1, 1b91c597b0214b1b462eb627ec02658c944623f2, 25195f9d5ffcc8079ad743a50c0409dbdc48d98a, d60d493b0e65647e0335e6a7c4547abcea7df8e9, a527750d877fd334de87eef81f1cb5f0f0ca3373 |
| Linux/Linuxgeneric | 2.6.26 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
Published upstream
Feb 27, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 14, 2026
In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: add RCU protection to mld_newpack() mld_newpack() can be called without RTNL or RCU being held. Note that we no longer can use sock_alloc_send_skb() because ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep. Instead use alloc_skb() and charge the net->ipv6.igmp_sk socket under RCU protection.
Quoted source text, attributed separately from HOL analysis.