Answer in brief
CVE-2025-21703 records a Unknown severity vulnerability in netem: Update sch->q.qlen before qdisc_tree_reduce_backlog(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). 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-2025-21703 records a Unknown severity vulnerability in netem: Update sch->q.qlen before qdisc_tree_reduce_backlog(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. 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). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31 <e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c || >=216509dda290f6db92c816dd54b83c1df9da9e76 <7f31d74fcc556a9166b1bb20515542de7bb939d1 || >=c2047b0e216c8edce227d7c42f99ac2877dad0e4 <98a2c685293aae122f688cde11d9334dddc5d207 || >=10df49cfca73dfbbdb6c4150d859f7e8926ae427 <7b79ca9a1de6a428d486ff52fb3d602321c08f55 || >=3824c5fad18eeb7abe0c4fc966f29959552dca3e <1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5 || >=356078a5c55ec8d2061fcc009fb8599f5b0527f9 <6312555249082d6d8cc5321ff725df05482d8b83 || >=f8d4bc455047cf3903cd6f85f49978987dbb3027 <839ecc583fa00fab785fde1c85a326743657fd32 || >=f8d4bc455047cf3903cd6f85f49978987dbb3027 <638ba5089324796c2ee49af10427459c2de35f71 || >=5.4.288 <5.4.291 || >=5.10.232 <5.10.235 || >=5.15.175 <5.15.179 || >=6.1.121 <6.1.129 || >=6.6.67 <6.6.78 || >=6.12.6 <6.12.14 | e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c, 7f31d74fcc556a9166b1bb20515542de7bb939d1, 98a2c685293aae122f688cde11d9334dddc5d207, 7b79ca9a1de6a428d486ff52fb3d602321c08f55, 1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5, 6312555249082d6d8cc5321ff725df05482d8b83, 839ecc583fa00fab785fde1c85a326743657fd32, 638ba5089324796c2ee49af10427459c2de35f71, 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.78, 6.12.14 |
| Linux/Linuxgeneric | 6.13 | Not reported |
Published upstream
Feb 18, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.
Quoted source text, attributed separately from HOL analysis.
A CVSS score is not reported in the current record. 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). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31 <e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c || >=216509dda290f6db92c816dd54b83c1df9da9e76 <7f31d74fcc556a9166b1bb20515542de7bb939d1 || >=c2047b0e216c8edce227d7c42f99ac2877dad0e4 <98a2c685293aae122f688cde11d9334dddc5d207 || >=10df49cfca73dfbbdb6c4150d859f7e8926ae427 <7b79ca9a1de6a428d486ff52fb3d602321c08f55 || >=3824c5fad18eeb7abe0c4fc966f29959552dca3e <1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5 || >=356078a5c55ec8d2061fcc009fb8599f5b0527f9 <6312555249082d6d8cc5321ff725df05482d8b83 || >=f8d4bc455047cf3903cd6f85f49978987dbb3027 <839ecc583fa00fab785fde1c85a326743657fd32 || >=f8d4bc455047cf3903cd6f85f49978987dbb3027 <638ba5089324796c2ee49af10427459c2de35f71 || >=5.4.288 <5.4.291 || >=5.10.232 <5.10.235 || >=5.15.175 <5.15.179 || >=6.1.121 <6.1.129 || >=6.6.67 <6.6.78 || >=6.12.6 <6.12.14 | e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c, 7f31d74fcc556a9166b1bb20515542de7bb939d1, 98a2c685293aae122f688cde11d9334dddc5d207, 7b79ca9a1de6a428d486ff52fb3d602321c08f55, 1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5, 6312555249082d6d8cc5321ff725df05482d8b83, 839ecc583fa00fab785fde1c85a326743657fd32, 638ba5089324796c2ee49af10427459c2de35f71, 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.78, 6.12.14 |
| Linux/Linuxgeneric | 6.13 | Not reported |
Published upstream
Feb 18, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.
Quoted source text, attributed separately from HOL analysis.