Bug 2491468 (CVE-2026-54275)

Summary: CVE-2026-54275 aiohttp: AIOHTTP: TLS SNI check bypass via connection reuse
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: adudiak, alinfoot, anpicker, anthomas, aprice, bbrownin, bdettelb, bparees, brasmith, cochase, dfreiber, doconnor, dranck, drow, dschmidt, dtrifiro, ehelms, erezende, ggainey, gtanzill, hasun, ilpinto, jburrell, jbuscemi, jdobes, jfula, jkoehler, jlanda, jmitchel, jowilson, jsamir, juwatts, jwong, kaycoth, kshier, lbrazdil, lichen, ljawale, lphiri, ltomasbo, luizcosta, mbarnett, mhulan, mminar, nmoumoul, nweather, nyancey, oezr, omaciel, ometelka, orabin, osousa, pakotvan, pbohmill, pcreech, ptisnovs, rbiba, rbobbitt, rbryant, rchan, rjohnson, simaishi, smallamp, sskracic, stcannon, sthirugn, syedriko, teagle, tmalecek, tpfromme, ttakamiy, vkumar, weaton, xdharmai, xialiu, yguenane, ykashtan, zzhou
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in aiohttp, an asynchronous HTTP client/server framework. This vulnerability allows a remote attacker to bypass the Transport Layer Security (TLS) Server Name Indication (SNI) check. This occurs when an application reuses an existing connection for multiple requests to the same domain but with different server_hostname parameters. Consequently, later requests may succeed by reusing the existing connection, even if they should have been rejected due to the TLS SNI check, potentially leading to unintended information disclosure or integrity issues.
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Description OSIDB Bzimport 2026-06-22 18:03:12 UTC 
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, the server_hostname TLS SNI check can be bypassed when an existing connection is reused. If an application makes multiple requests to the same domain, but with different per-request server_hostname parameters, then the later calls may succeed by reusing the existing connection when they should have been rejected due to the TLS SNI check. This vulnerability is fixed in 3.14.1.