CVE-2026-74577

UNRATEDCVSS · not yet scoredTrending — 5 sources updated this week
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EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS v2: —Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In the Linux kernel, the following vulnerability has been resolved:

net: mpls: initialize rtm_tos in mpls_getroute()

mpls_getroute() builds the RTM_NEWROUTE reply to an RTM_GETROUTE request by filling a struct rtmsg allocated from an skb whose data area is not zeroed (alloc_skb(NLMSG_GOODSIZE, ...)). It sets every field of the header except rtm_tos:

r = nlmsg_data(nlh); r->rtm_family = AF_MPLS; r->rtm_dst_len = 20; r->rtm_src_len = 0; r->rtm_table = RT_TABLE_MAIN; r->rtm_type = RTN_UNICAST; r->rtm_scope = RT_SCOPE_UNIVERSE; r->rtm_protocol = rt->rt_protocol; r->rtm_flags = 0;

struct rtmsg has no padding, so the one uninitialised byte rtm_tos (offset 3) is copied straight to user space on recvmsg(), leaking a byte of uninitialised heap memory. This is in contrast to mpls_dump_route(), which fills the very same header and does set rtm_tos = 0.

Initialize rtm_tos to 0, matching mpls_dump_route().

Reproduced with KMSAN by adding an MPLS route and issuing a non-RTM_F_FIB_MATCH RTM_GETROUTE for its label:

BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x36c/0x33f0 _copy_to_iter+0x36c/0x33f0 __skb_datagram_iter+0x196/0x12c0 skb_copy_datagram_iter+0x5b/0x210 netlink_recvmsg+0x37b/0xef0 ... Uninit was created at: __alloc_skb+0x8ca/0x10e0 mpls_getroute+0x1280/0x3a40 rtnetlink_rcv_msg+0x1138/0x15a0 ... Byte 19 of 64 is uninitialized

(byte 19 = nlmsghdr(16) + rtmsg offset 3 = rtm_tos)

CVSS v3
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EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
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EG Risk
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EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

August 15, 2026

Last Modified

August 19, 2026

References (8)

Vendor Advisories for CVE-2026-74577(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Data Freshness Timeline

(refreshed 19× in last 7d / 19× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-20 22:56 UTCEPSS rescore
  2. 2026-08-19 17:38 UTCGHSA enrichment
  3. 2026-08-19 17:34 UTCNVD update
  4. 2026-08-19 17:04 UTCEPSS rescore
  5. 2026-08-19 16:52 UTCGHSA enrichment
  6. 2026-08-19 16:52 UTCMITRE cvelistV5
  7. 2026-08-18 13:49 UTCEPSS rescore
  8. 2026-08-18 13:49 UTCEPSS rescore
  9. 2026-08-17 13:47 UTCEPSS rescore
  10. 2026-08-17 06:23 UTCGHSA enrichment
  11. 2026-08-17 06:23 UTCNVD update
  12. 2026-08-17 05:39 UTCEG score recompute
  13. 2026-08-17 05:39 UTCGHSA enrichment
  14. 2026-08-17 05:39 UTCMITRE cvelistV5
  15. 2026-08-16 14:56 UTCEPSS rescore
  16. 2026-08-16 14:56 UTCEPSS rescore
  17. 2026-08-15 13:27 UTCNVD update
  18. 2026-08-15 12:38 UTCEG score recompute
  19. 2026-08-15 12:37 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-74577?
CVE-2026-74577 is a publicly disclosed vulnerability published on August 15, 2026. In the Linux kernel, the following vulnerability has been resolved: net: mpls: initialize rtmtos in mplsgetroute() mplsgetroute() builds the RTMNEWROUTE reply to an RTM_GETROUTE request by filling a struct rtmsg allocated from an skb whose data area is not zeroed (allocskb(NLMSGGOODSIZE, ...)). It…
When was CVE-2026-74577 disclosed?
CVE-2026-74577 was first published in the National Vulnerability Database on August 15, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-74577 actively exploited?
CVE-2026-74577 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 93.8% of all scored CVEs.
How do I remediate CVE-2026-74577?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-74577, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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